I have a SP 404SX for triggering one shot samples/FX (not that cheap)
And MFB Nanozwerg (cheap) being sequenced by OT and then goes into OT for FX, sounds nice, but I found out that for Live Shows I really need a synth with a Master Volume knob, might take a Mono Lancet (which also has midi thru, by the way.)
Roland GP-8 - rack version of some early boss pedals… analog distortion, turbo overdrive, dynamic filter (uses ir3109 from juno60/jx3p), compressor, phaser, eq, digital delay & digital chorus (sounds awesome).
Paid $60 about 4 yrs ago.
art v3 tube preamp - been useful for boosting levels of quiet synths (does nice things to a yamaha CS10) as well as microphones & guitar levels into Octatrack. Not a lot of tube mojo but it gets used a lot.
Midi Solutions Merger - Been useful for a bunch of different tasks.
the critter & guitari stuff is cheap for boutique. i’ve had pocket piano GR for a couple years and just added bolsa bass for MIDI goodness. each one only does 5-6 things but they do them so well. just fun and eye-catching too - “delightful” was a friend’s initial reaction.
seconded on the meeblip, especially if you, uh, like aliasing
While not exactly cheap (anymore) the Yamaha DX200 is the shit.
Can still be found on ebay for $300-500.
The only FM groovebox out there that I’m aware of.
Basically a 6 operator FM synth in a box with step sequencer and knobs !!!
Multimode filter and FX
Will load DX7 patches (of which there are loads of available online)
Note the use of scene control in the top left with a crossfader knob for morphing between sounds. Similar in function to the OT crossfader.
Lost a bid on one of these last year. Will try again this year.
They sound exactly like you think an FM synth with loads of knobs might sound. Savage !