Renting the 50mm 1.0 is in the ball park of not quite twice as much as renting the 50mm 1.2 or the 85mm 1.2. I kinda figured the 85mm would be the way to go. I don't think I'd ever buy a 50mm 1.0 even if I had the 5k or so to blow on it. Not only does it sound like the 50mm 1.2 performs better, but the 50mm 1.0 is quite likely unrepairable if anything ever happens to it. Also, while I am sure I have spent far more than the average person on camera gear, I'm no collector.

I'm very careful with my lenses, however accidents happen (I'm actually putting together a list of camera gear to send to my insurance company). It's in the area of $9.00 a month to insure it all, but the one time I actually dropped a lens and had to have it repaired ran the usual $250. That would have paid for more than two years of insurance alone. Luckily we'd already been through the city where it was most useful.

I have...
Canon 10-22mm EF-S 3.5-4.5
Tamron 17-50mm 2.8 XR Di II
Canon 17-55mm EF-S 2.8
Canon 24-104mm L EF 4.0
Sigma 30mm 1.4 EX DC HSM
Canon 70-200mm L EF IS 2.8
Canon 100mm EF 2.8
Sigma 120-400mm 4.5-5.6 DG OS HSM APO

I'm looking to pick up...
Canon 65mm x1-5 Macro
Canon 85mm L 2.8 ...and/or... Canon 50mm L 1.2
Canon 100-400mm L 4.5-5.6
...and one of the fisheyes (possibly the Sigma 4.5mm or 10mm depending on if I want circular or rectangular photos).

Someday I might get the 100mm L 2.8 Macro, but the only reason I can see to buy it right now is for the IS, which I don't really need. The Fiancees 100mm 2.8 is one of the sharpest lenses we have (and the 10-22mm performs remarkably well too).