We are interested in Auto Water Pump For NISSAN/DATSUN GMB:GWN-01A GMB:150-1010 NPW:N-1 QH:QCP2444 AIRTEX:AW9179 SIL:PA1044 21010-13200 21010-13201 21010-13202.What is the price for a sample?If we proceed what are the costs for a bulk purchase of 50 units per time?