Thank you!
Yafaray is pretty good. It is one of the best at easily transfering materials over from Blender to another renderer. It now has it's own materials panels where you can set up mats separately, but usually it will 'remember' well if you already have mats set up in Blender and you swap over. You can get some brilliant renders and it's relatively fast. Cycles is very good, but it's still alpha, so there are a few things not there yet (like transparency). But I think that when it's closer to beta, I'm going to jump ship. The great thing about Cycles is that it's 'live'. The viewport is continously updating and it is great for checking materials and lighting changes. As it's constantly updating, you don't have to wait. One good one I'm looking at is
LuxRender. I think it gives more realistic results, but it's very slow. As I said earlier, it's now got a few speed bumps, so I'd check it out as well. You can get some decent results from Blender's internal renderer. I'm looking at
this tut at the moment.
A good place to get hold of the latest builds of these things is
Graphicall.org, where you can download pre-made builds of Blender with different renderers built-in. Just download, upzip and click on the render tab to swap over to the renderer you want to try out.
One thing to keep in mind is
Kerkythea. You could take your model straight into it directly from your CAD program and not have to touch Blender at all. It has it's own lighting studio built in. The only thing with it is that it's 'legacy' which means that it's not being actively updated anymore, but it is being maintained.
Turbo Squid is OK. You need a shed-load of stuff up there to really make a lot of money.