Based on vague recollection, I've seen MP2s going for around $400-450 and ADC-20s going for around $175-225.
As for the battery packs, depends on what size, cables included, age and usage, etc. Considering they're so easy to make...I'd sell 'em cheap.
I usually give discounts for selling bunches of stuff together because it's much less hassle than selling each piece individually.