Even if you already made your decision, I was in a similiar position recently and here's what I did. I'll echo the "don't by new" sentiment and buy a certified used one with low miles. When you factor in the extended (12yr/12kmile) warranty, you're usually covered just as long as you would be with a new car purchase. PM me if you want more information on finding a great deal on these. If you do that, I would throw out the idea of buying a newer cheaper car (like the civic), if the tsx is really worth that much to you. It comes down to whether you want to buy something much cheaper and own much sooner (but face possible mech. problems) or get yourself into more debt and buy newer.
Sure, the financial costs of driving your newer car will be higher, but if you intend on keeping the car for a long period of time and derive lots of utility from having a nicer car... go for it. On the other hand, there's nothing like having a clunker that you can fill with cheap gas, park in the tightest parking spaces around, and drive like wear and tear doesn't have any effect on the car.
Once you buy the car, make sure to maintain it well. You have a great starting salary for your age, so with no other major expenses, I'd say buy it. The resale value on these cars is high, so you can always turn around and sell it if you really get into a bind.