Try Pick & Pull, 33rd & Peoria in Aurora. The paper is also a good place, but it isn't quite the same since the whole JOA thing started. Front 60s are hard to come by, around a grand seems the norm. I paid $750 from Denver Used Pickup, I just happened to call the morning after they got a K30 in. This was after looking everyday farily seriously for a year. As far as front 3/4 ton 44s or 10 bolts, $200 seems like a good price around here. IF you're looking at 3/4 fronts, don't be afraid of 10 bolts, they seem to be more available and are really no better/worse than 44s. If you can, though, I'd hold out for a 60 if you plan to do any serious wheeling, it'll save $ in the long run.
Pete
'83 K5, 350 TBI (ex 6.2), 700R4, NP208, Dana 60/14 bolt, 4.56s, Detroits, 3" lift, 15-39.5x15 TSLs
'97 Dodge 2500 4x4 CC LB Sport, Cummins 5 spd