If you tinker with your own car, you'll know how difficult it can be sometimes to find the right parts quickly. Do you go to the local store? Do you look online? When you're online, how do you know that company A has a better price than company B? Who actually has it in stock?
If you go the internet route, it's easy to waste half an hour or more banging through search sites and dealers trying to get to the bottom of that particular can of worms. But I recently came across a site that's a bit more clever than most. It's like an aggregated list of many online vendors. You put in the part you want (from the list of available vehicles and parts) and the site then shows you a whole load of online vendors who have it in stock, with the price. So you can click through and buy the part pretty easily from there. There might be other sites out there that do the same thing but I've not see one before, so this is still a novelty for me. It's American-market only right now.
The site has an odd name but I think it's worth checking out - OEMcats.com