Level 161 parts used to sell for a LOT more to the shop (+4 head was about 400k), so that's why ppl could farm for those parts on lv 172 and actually make enough to buy super expensive things. They have since dropped the value of this parts buy an incredible amount, though, so it's pretty much impossible to get enough money by farming any more. Selling farmed items/event items to players that already have money back from when it was easier to get is going to be your best bet now.