I've thrown three bachelor parties in the last year and a half (my brother, best friend, and another good friend). It really depends on what you're doing. I've always wanted to do the Vegas thing but I couldn't get everyone else to go due to work issues. Also depends if you're asking the others to throw in on things.
I spent about $2000 at each. It broke down basically like this:
$800 for 2 girls to show up (you can pay less but they may not have all their teeth)
$200 on beer (I always ask everyone else to bring the liquor)
$500 for hotel rooms
$500 for assorted crap, dinner at a restaurant before, and tips
... and of course, tell your friends to bring money for tips (singles, fives, and tens). I swear, only like 1 out of every dozen guys will actually bring that. Then you've got 11 guys standing around with $50 bills like wtf.
If you're going to get "entertainment" for the hotel later, make sure you SEE THEM FIRST. Don't just go on a website pic or from word of mouth.