I've posted this before, I've had e-liquids from vendors that others have raved about that I didn't care for, and bargain basement e-liquids that I really liked.
As far as inexpensive e-liquids go, my favorite is Mount Baker Vapor, and their customer service is great.
If you know what sort of flavors you like (or may be interested in), I'd start, as Spencer87 suggested, with our registered suppliers, and go from there!