Well, I don't know your comfort level, or skill, but I have seen lots harder things than this done on this forum.
So, here goes.
http://www.amazon.com/Small-Metal-Rubber-Parts-Edition/dp/0830604146/
I bought this book back when it was new, and repaired several things that could no longer be bought.
Pretty sure that there are better books now, and probably better stuff than the old Devcon Flexane.
Do a search on casting rubber parts and see what is out there.
If you can find a decent gasket to make a mold of, you should be able to cast your own. Make a mold out of something soft enough, and you can "adjust" it with an exacto knife to make the part closer to what you need.
And, don't rule out repairing what you have with some of the two part compounds.
Or, if you have a gasket that is squished between two doors, and has shrunk too much, you can coat the other door with silicone release agent, mold a bunch of soft silicone rubber on the old part, and gently close the door.
After it hardens, ease the doors open, remove the part, trim up the excess stuff and use it to make a mold to cast a new part.
Get a decent mold made, you can run off as many gaskets as you want and spread the love among others.
With kind of money numbers you are throwing around, its worth a try.