I see a lot of them going for upwards of $100 on craigslist in my area, so based on that you didn't do too bad at all. I'm partially biased, considering I got mine for free.

The Vivitar 28mm should be pretty fun, and the 50mm's are classic, excellent lenses. Are they new-FD (all black plastic) or old FD (chrome bayonet)? And yes, you can call the DOF thingy a slide.