I made a similar rationalization. After just once on the slopes for the first time using rented equipment I did some number crunching and it was far better to buy my own stuff and not have to fight rental lines, get there 4 hrs before the place opens, etc. So the next day or two I spent about $1,000 on equipment to get me up to speed: used board, new boots, and new bindings.
I knew the boots and bindings could be sold if I ended up not pursuing the sport since they are new so that helped. Also, for my previous car, a single set of summer tires were close to $800-$1,000 and only lasted one year. Ugh. This stuff will (hopefully) last me 5-10 years. At least, that was the reason I gave my wife and it seemed to work.