mark-
as for your midi request, i have no idea. a world i don't to this day understand.
for small, cheap-
adrenalinns-i had a II, & thought the drum machine was awesome in it (favored dance/groove stuff), & it's smallish, i almost think about getting 1 again just for the drum machine
zoom g2 / digitech rp150 small table top multi-effects have limited drum machines in them. they're ok, these usually can be gotten cheap.
i would guess your best bet would be one of the
boss units or
alessis unit
as for the m-audio black box-i had one, briefly a few yrs ago, good sounds, again, cool drum machine in it, but i didn't think it was too "smallish" it is table top, but it's
quite thick (i thought). feel wise it seems to remind me a bit of size of line 6 pod bean thing (maybe ht/width smaller, but depth-much thicker than pod)-i guess you can judge
if that seems too big for you.
(ps-i
don't think the above things i mentioned will fill your midi option)
i just did an ebay search for "drum machine" pop in cheapest, seemed to be a bunch of funky things that come up, good luck if descriptions give you all the data you need about it.
happy search!
s---
www.myspace.com/scotthansen