Be wary of gladiators outside the colosseum. They don't take photos for free and can be quite agressive about their payment. Also don't be fooled into taking an unlicensed guided tour of the Colosseum either....
14 000 ft!
DO IT!
It may seem like a lot of money at the time but it is worth every cent! Make sure you buy the video so you can prove it to all of your friends!