I payed for D3 beta access a few months ago... I really wanted to try it out since I had nothing else I wanted to play. Was about 40$ for 8 hours.
For me it was worth it, some have been waiting for the game so long that they feel like they are going insane. There are many games out there that are completely worthless to buy. The sum isn't that much. Don't kid yourself, you can end up paying double (triple) the amount one night out with your friends.
Sometimes it's just worth it to reduce the urge...
I actually am selling mine currently, only problem being is that my main selling point is infact the WoW account, and not the D3 beta (aswell as every other Blizz game on it)... turns out wow accounts are extremely hard to sell right now, or i'm being unlucky, cause it's been up for months and barely any interest (even with D3 beta on it and advertised as such)