Do it! I just finished my setup a few days ago, and holy crap was it worth it!
I'm running 2 6870's in CF and they push 3 1080 Asus' very well. The Asus' are temporary until I can save up in a few weeks for the Samsung 230X3 setup.
I've had SLI Nvidia cards for years! IIRC, I've had 6800s, 8800s, 9600s, 280s, and 470s in SLI. I just recently switch to ATI for Eyefinity and I do not regret it so far in the slightest!
OP - this has always been my moto in life. If it's that big of a hobby for you in your life (referring to anything, in this case, gaming), don't hold back!
I've always said if you're into gaming that much, there are 3 things you go all out on. (Edit: misworded. Go with a nice setup rather than all out! =) Don't break yourself)
3. Chair (seriously overlooked by so many people, unfortunately)
Do it Op, and do not regret it. Work overtime at your job to make up for it if an option, but Eyefinity is the bomb! And if you play shooters, it'll give you an edge over your competition.
GL with your decision!
Edited by Sicc - 2/1/11 at 11:50pm