As mentioned elsewhere I bought myself a triple bench supply recently.
It’s a Chinese made unit with two variable supplies up to 30 V, 3 A and a fixed 5 V supply. The two variable supplies can be used independently, in series, or in parallel. Obviously this is way beyond what you need for testing synth modules, which is all I’ve used it for so far.
I’ve seen this (HY3003F-3 under various brand names) listed for $170 to $200 new. I bought mine used from ValueTronics International (located in Elgin, IL, USA) for $60, plus $20 shipping to my US address. It was shipped quickly and well (in a box full of packing peanuts, though, which I hate having to deal with).
It has some scuffing on one side but otherwise looks pretty much like new. So far as I have been able to tell it works perfectly. The variable supplies can be set up for fixed voltage or current. The + and - outputs float, so either can be tied to ground — one of each to make a ±12 V (or ± whatever up to 30 V) supply.
The displays are bright and easy to read. Red for current and green for voltage helps readability, at least if you’re not colorblind. Resolution is limited to 100 mV and 10 mA, but that’s good enough for my immediate needs. (Certainly the current readout is good enough to distinguish “ok looks good so far” from “oh shit turn it off!!”)
I haven’t checked the accuracy of the current displays but my multimeter says the voltage displays are dead on.
I’m happy with my purchase and would definitely recommend looking into getting one from ValueTronics if it’s the sort of thing you’re feeling the need for.