Avoid doing this if you can learn to get used to the yellowed cases. The reason to not retrobright is that it damages the plastic and it's easy to get it wrong and end up with a case that looks even worse than when you started. Even if you retrobright, the plastic will yellow again unless it's UV treated but at the end of the day, these are 30+ year old machines so you may as well enjoy them as they are.
Take a look at ZuluSCSI:
http://zuluscsi.com/
Well, the SE is generally a better machine for old B&W games vs. an SE/30 because a lot of those games don't work with the 68030 processor whereas they work fine on a 68000 like the SE has. I have multiple SE/30s but I actually chose to get an SE for this reason.
That's a good price for them. And has has been mentioned, that is a IIgs keyboard which is sought after - it has a different feel to the other keyboards they made.
The other keyboard you got is an AppleDesign Keyboard, most of which are not mechanical and have a spongy feel to them - not very desirable and generally not well liked by Mac collectors. At one point I had about 15 of those keyboards and I gave them all away, didn't even keep one for myself. The only spongy style keyboards I kept in my collection are Apple Keyboard IIs, but the rest of my Apple keyboards are mechanical.