I built my current PC (Ryzen 3700X, MSI B450-A Pro Max, Kingston 500GB M.2, 16GB Klevv Bolt DDR4) for around £300 - CPU and motherboard cost me around £200 (refurbished) and the RAM and M.2 (new) were £50 each - sadly it's hard to find those kind of prices now.
ebay got involved and decided to side with the buyer, I was fobbed off and lied to on the phone by them and they refused to budge until I found the address of their Uk headquarters and issued them a small claims and I won by default as they did't even respond back.