So your budget is around $500... For that, there are several old real analog synths you could get. Of course, you;d have to deal with eBay or a used shop or the classifieds, and all the problems that come with real analog synths (tuning instability, sticky stuff, weird MIDI implementations, lack of velocity sensitivity, osciallator drift)...
You could also look at a Nord MicroModular, for around $550. This is a really cool little synth, but you do all the editing on your computer, and it only has 4 voices. Still, Nord is famous for phatness for good reason.
Yea I was looking at the A station, u think it hits harder than the MS2000R and u think it a better value. I think it has 200 presets and the MS2000R has 128.