Ebay can be a great source for parts inexpensively. Of course, it can also be a source of questionable products and sellers, so if you are unfamiliar with it, you mean want to learn how the feedback system works and how to avoid common scams.
For example: I've had very good luck over the years, with only a few "clinkers". I have been able to get a set of 4 OEM rims for an old car for $100, where the dealer wanted $500 each. Of the 4, 2 were usable. On the other hand, I only really needed one. I've also found a variety of other parts at good prices.