It'll depend on whether you need to play one octave pedals,straight, or more, radials. Some time ago, I used the pedalboard from an oldish Hammond two manual + 1 octave pedals, and re-wired them to make a separate pedal 'manual'. This was then MIDId through whatever synth I fancy, and works well. I guess you could find a two octave pedalboard if needed, and do the same. Got to say, it was a nice little project, and works well - there's also a Nanobass synth that fits with it, for a plethora of bass sounds.And a darn sight cheaper than those advertised...
Any synth or workstation will do the manual job for you, as they generally have the organ touch, so for not a lot, you could set yourself up with one/two manuals and the pedals below. And loads and loads of other sounds, apart from the inevitable (and gorgeous) Hammond sounds.