Don't forget most rental houses require 1,000,000 dollar general liability insurance and insurance on the equipment. The cheapest premium for liability I found was 2500.00 US. Needless to say my micro-budget film is now being shot without the adapter.
There are some insurance places that will give you insurance for $300 a day.. but still its a little retarted, spending a grand a day for the adapter and insurance and another grand a day on some nice Primes.
You really need to be doing something special to put up the dough. I actually do know someone here that bought one for his XL1, and rents it out. Well, he basically gives it away now because not that many people wanna use the XL1 anymore, as with the resolution loss on the adapter and the low rez on the XL1 its kinda bad. Regardless, if it fits his Xl2 mabe he will make his investment back.