I have a bit of a dilemma. I'm going to Ottawa in a few weeks and I want to have a ultra-wide angle lens for the trip (cool buildings and all) and it is justified because I do mostly landscape and travel photography anyway.

So I was going to buy the Sigma 10-20mm 4-5.6 for my Nikon D5000, but then I found a place that rents lenses and I can rent a Nikon 10-24 3.5-4.5 rather cheaply for the weekend (or a 12-24 for the same cost). But I would like a wide-angle lens to own, as I again do lots of travel and landscape stuff. So should I just buy the Sigma now or rent the Nikon and save my money to get something better in a few months time (when I get my taxes back and have about $1000 for a lens)? And if I should wait what lens would you suggest at that time (keeping in mind I have no internal motor, so sadly no Tokina 11-16)?

Thx /p/, sorry for the gear thread...