Getting it done by Christmas and not wanting to paint it or have free time to work on it means you will need serious funds. There really is no way to get something of even decent quality together -- in relatively short order -- without cash to spend.
I would watch The Cargo Hold and act quickly on anything you see you might want -- things go fast! You can also try the following websites for more ready made stuff and ask the vendors about timing and costs:
http://www.bobamaker.co.uk/ -- Daz makes just about everything and quality is unquestioned. He also offers fully painted pieces, but that doesn't come cheap and it may take two months or more to get it, so you'd need to act soon.
http://www.freewebs.com/wickedbeard/ -- Jeff also makes great stuff -- metal armor, gauntlets, etc -- and offers them fully painted too. He also posts prices on his site so it's easy to see what everything costs and he's also just a nice guy to deal with.
http://ladysewforus.com/ -- a FANTASTIC place for soft goods - jumpsuits, vest, spats, pouches, etc.
You can surf eBay, but you do so at your own risk. Lots of stuff there is Monet -- looks good from a distance but like **** up close. People here put items there from time to time and there are a couple of sellers I've heard are decent like cucblack, but you are better off finding stuff here. You can always solicit painting and assembly services from any of the many able bodied artisans on the site.
Good luck!
Chris