Is there a MacLea family tartan?
Ah, the immortal question!
When I got married, I chose to get my kilt in a given tartan by a couple of criteria. The first was what I considered to be reasonable and appropriate. McLeas have traditionally (according to the surname books) been thought to be members of the clan Stewart of Appin, so that tartan pattern was a possibility. Royal Stewart, Black Watch, Scottish National, and a number of other tartans are 'open' to anyone who wants to wear them. There is no real regulation on tartans, but many people think that you should have permission of the chief of a clan, either by virtue of birth or recognition, to wear that chief's tartan. This is not strictly required though.
The other choice would be to choose the tartan of the Clan McLea/Livingstone. Though the McLeas are a Highland family and not known to be related to the Lowland Livingston clan, the clan McLea has not chosen a separate tartan. The clan chief of McLea wears the Livingston tartan. As has been pointed out, since the Lowland Livingstons were not highlanders at all, it is unclear that they would have ever worn tartan at all, except as a later harkening back to old Scottish traditions. It is equally likely, then, that this tartan may be in fact more appropriate for Highland McLeas/Livingstones than for the Lowlanders with whom the tartan is now associated.
In consulting with the son of the Chief of McLea, the Young Bachuil, I discovered that the current Chief prefers the Ancient Colors of the Livingston tartan (an orange base meant to resemble old vegetable dyes) most of the time. The Young Bachuil himself has a fondness for the Muted version of the tartan, which is lovely as well. Though we have no proven blood relationship with the Chiefs of MacLea (which in Scottish parlance would be called an "indeterminate cadet"), the current Chief extended to me his permission for our family to wear the Livingston tartan as a token of our association with his clan.
I chose to follow his lead and wear the Livingston tartan but because of the colors in our wedding, I chose to get my kilt in the Livingston Modern Colors (which have red as a base color). If you chose to do the same, look for "Livingston" or "Livingston Modern" as the name of the tartan. McLay is another tartan thought to be very appropriate for the Highland McLea family as well. And for the ladies, the Livingston Dress tartan is an attractive choice.
But there are also many other choices (there are tartans for many states in USA, US branches of the military, Scottish heritage organizations, regions in Scotland rather than clans, and a number of nice other tartans too). I would suggest that there is no 'right' tartan and that any one of them would make a lovely kilt or blanket or whatnot.
You can find pictures and lists of tartans at almost any Scottish shop, online or in their catalog.
A side note on kilts
Kilts, the unbifurcated Scottish national garment, are pleated in the back either 'to sett,' or 'to stripe.' Most of the time, men who are non-military and not marching in a pipe band choose to get their kilts pleated 'to sett.' 'To stripe' is more expensive, because it uses more fabric, and with some tartans it doesn't work very well, depending on the sett. When you order, they will give you all the measurements you need to make to have it fit properly. Since kilts cannot easily be 'taken out' or 'taken in' you need to be very good with the measuring!
If you want to learn about wearing the kilt, I'd recommend picking up a copy of So You're Going to Wear the Kilt, 3rd edition, by J. Charles Thompson, which will talk a lot more about this.
I bought my kilt from the Scottish Lion, before they were sold to a different company upon the retirement of the owners. Their new address is: http://www.scottishlion.com/customkilts.html. Other good choices are the Scottish Merchant (http://www.scottishmerchant.com) and the Scottish Tartans Museum (http://giftshop.scottishtartans.org/kiltpage.html). Most of these places buy them from Scotland anyway and have them shipped, so I'm guessing it can't really be that different!
You can also buy yards of tartan fabric and have them make you some kind of wall hanging from that if you prefer.
What about MacLea clan crest badges and similar?
The McLea clan (http://www.clanmclea.co.uk) is a newly recognized clan in Scotland, despite its antiquity. As a result, none of the companies that make all the other clan crest badges and other accoutrements make a McLea crest yet. So, if you want one, you'll have to be patient while they are designed. For one who chooses to show his allegiance to the chief of the Clan as a member of a clan, you are entitled to wear the chief's arms encircled by a strap and buckle (you can see this in all the other clans' crests). Only the chief himself is allowed to wear the crest in a plain circlet or other device. For your information, the blazon (or heraldic description) of the Clan Crest badge is this: A demi-man representing the figure of Saint Moluag Proper, his head ensigned of a circle of glory Or, having about his shoulders a cloak Vert, holding in his dexter hand the great Staff of Saint Moluag Proper and in his sinister hand a cross crosslet fitchee Azure. The motto of the clan is Cnoc Aingeil, the name of a location on the Isle of Lismore that is home to the McLea Chief.
Despite the fact that the Livingston tartan probably represents the McLea family's proper tartan, the clan crest badge that is commonly available under Livingston is a different story. The commonly available Livinston badge is that of the lowland Livingstons, with the motto Si je puis (If I can) and the badge consisting of a A demi-savage wreathed about the head and middle with laurel leaves, in dexter a club, in sinister a serpent entwined round the arm, all proper. There is no known relationship between the Lowland Livingstons and the Highland Livingstones (the McLeas).
Given the commonly-held view of the surname books that our family owes its allegiance to the clan Stewart of Appin, it may be appropriate to wear the clan crest badge of the Stewarts of Appin (a Unicorn's head) as well. (Note, though, that it is not clear what relationship the MacLeas had with the Stewarts. It may be that this association with the Stewarts of Appin is exaggerated. However, there is clear evidence that many McLeas fought with the Stewarts during the 1745 Rising, now known as the Second Jacobite Rebellion).
It is really up to you!