the high density garmin pins are available on ebay from time to time. stein stocks the others at $25 per 100. (he may stock the high density pins also, but i got a good deal off ebay.)
only ever needed the male pins in the high density size. the gtx320 uses regular density female pins. the 430 uses both high-density and regular male pins (iirc -- it's been a coupla months since i did these).