If you've budgeted for the purchase, and it's not just a crazy splurge - I would say don't beat your self up too much. You deserve to be happy and to treat yourself every now and then.

As long as you're being financially responsible about it, a "me gift" is totally acceptable every now and then.

I've been doing that kind of thing recently with getting myself clothes from the company I work for. I wait to order till stuff is on clearance, 70% off or better, so I can outfit my family in expensive gear for not a lot of dough. Rather than feeling guilty about buying things that, ostensibly speaking I may not exactly "need", I just focus on the fact that I'm preparing for the future (always buying things out of season) and congratulate myself on the great deal/price I get.

Have an awesome weekend!