Out in the Nova Scotia woods

[Meadcrafter]

I might make a cape out of some fabric from the fabric store or just use some length of wide tartan maybe I can find.

Watch some of the sites that sell tartan by the yard. Sometimes they have pieces on sale cheap in their clearance section.

Like the look.

[Dale Seago]

I totally like the look and the expedient use of available fabrics. For some sort of cloakish wrap, I think you want something like a shepherd's plaid, also known as a day or laird's plaid:

http://giftshop.scottishtartans.org/...rds_plaid.html

It doesn't need to be in the same sett/colors as your kilt, don't worry about matching them.

You may also notice I said "something like" a shepherd's plaid. I understand your financial situation, and tartan fabric from Scotland is not known for being cheap, though Meadcrafter makes an excellent suggestion about looking for sales on tartan yardage.
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And you needn't restrict yourself to "proper" tartan from Scotland, as you can find plenty of other wool "tartanish" or tweed fabrics elsewhere for less. For example, pages and pages of 'em in heavyweight/coating fabric here:

http://www.fashionfabricsclub.com/se...s=wool+coating

(Prices shown are in US dollars.)

Those are 61" width, which is actually double the width you'd need. You might also look through bolts of cloth at a fabric store near you and see if there's something you like that you can have them just cut to the length you want and walk right out of the store with it.