Sourcing a used M54 engine

[ahlem]

Any suggestions on the best way to locate a good used engine? 2001 M54 for the X5. There is a debate going on at home about whether I should swap in a used motor or sell as-is. Mrs. doesn't think the effort will be worth it. Looking at the cost of a good used SUV these days makes me cringe and think a used motor is the way to go. If it was a plug and play, probably two weekends would do it. If I refresh gaskets, maybe a bit longer.