There is an aftermarket bot. And you don't need to buy them, it's for items already in the Inventory. But, yeah, it could easily be edited to buy 'em.
I've seen alot of vinyl hacks and paint hack but no after market on I'm suggesting the players who makes hacks show make an aftermarket one that buys the cheap 6000 IGC rims and the 6300 IGC rims I did this manually took me like 1 hour to get 500 aftermarket for the ford focus RS but but yeah like this:
1:Put the rims that cost 6300 IGC
2:install
3ut the rims that cost 6000 IGC
4:install
5:repeat this from 1-4
This isn't free obviously it cost a decent amount of IGC which is easy to earn back
But I only needed to install 300 parts which I spent about 1.7million IGC so maybe abou 2.2million for the full acheivment(500 parts)
This is just a suggestion but thinking now it's more of a macro than hack