Hi Paula, I have ordered several times from you and much appreciate your selection, prices and customer service!
One suggestion that I have regarding using pictures of parts you sell from us customers is that quality will vary wildly. Some use flash, some do not, some use a high-end SLR with proper color balancing and some do not (think indoor shots that are warm or orange looking). Also, different file sizes and types also need to be understood.
All this said, however, I believe a possible approach / solution would be to do what some other websites allow for and that is "customer action shots". This functionality, on your website, would allow a customer like me to take a picture of a product you sell on my vehicle and upload it to you. The upload process would specify file types accepted as well as size (e.g. 640 x 480 , .jpg or .gif). You would then have a person (maybe yourself) review and approve the picture (to ensure that it is appropriate) prior to posting to your site.
Here is an example of a website that uses this:
Camera Lens Mug :: ThinkGeek
Next to the Main Description tab (under the photo of the item) is a Customer Action Shots tab to click.
Good Luck!!