I think m9m is right, skip the PSS synths and go for a cheap 4-operator DX-series.
The DX21 is the best of the cheap 4-ops, but it doesn't compare to the DX11, which has crystal-clear DAC, velocity and aftertouch, and more powerful synthesis capabilities. The TX81Z is basically the rack version of the DX11, iirc.
The TX7 is a synth that I've bought and sold a couple times...It's exactly like a DX7 inside, but the only way you can program it, besides a few basic parameters, is with a computer editor/librarian program like MidiQuest.
The TX802 is a DX7-IID inside, but it's pretty hard to program at first. Steep learning curve. It has the best multitimbral capability of all of them, though. I really miss my DX7-IIFD.
If you wanted to get really crazy, you could find a TX816, which is 8 DX7's in a rack, but totally devoid of onboard editing.
My recommendation is either a DX21 or a DX11!