Well, here is a list.
1)LOBA/APR pump brand new
2)LOBA/APR second hand
3)Autotech internals in brand new pump
4)Autotech internals in second hand pump
5)Uknown internals in brand new pump
6)Unknown internals in second hand pump
There will be less risk the higher up the list you go, but the price will increase.
Ultimately its up to the buyer to decide what number they want to pick, based on risk vs price. So people have bought Autotech internals decided that was the right balance of risk/gain/price for them!