Cheapest pumps I've seen are $50 or $60 from eBay or Amazon. If you're going for a whole setup for $250 or less you may want to take a serious look at a springer. Cheapest you're going to do for a PCP decent setup is: $60 hpa handbpump from Amazon, a referb CenterPoint scope $75(I have the one in the link), and $200 for the refurbished Avenger.
BestEquip Airgun PCP Pump 4500PSI High Pressure Hand Pump 3 Stage Pump Chamber PCP Air Pump https://www.amazon.com/dp/B07CWRRPXL/ref=cm_sw_r_apan_i_KG9PT8J9EZ4GVY4R20GC