Usually, the biggest thing on my budget is the airplane ticket, if I am flying somewhere. To Europe, it usually costs 300 to 400$, then I usually stay with my friends over there. So I definitely save money by not going to hotels. When I need to, I usually go to youth hostels or campgrounds. I eat meals and so on. I could comfortably live off less than 50$ a day, unless I bought stuff like souvenirs and nice things to send back home. I would have to say I spend between 500$ to 1000$.
One time, I went to Europe for Spring Break with my ex, and it was like 380 roundtrip. Then we rent car for like 300 DM, plus petrol and so on. We stayed at some hotels, which was reasonable because both of us split the cost. That trip, we probably spent a bit more than 1000$. Filling up gas for car is very expensive...
I usually buy airplane tickets way in advance, and then it is over with and paid for. Then I try to budget as much as 1000$ and put a limit to myself for each day. I tend to be thrifty for spending money because I know that I can always buy things from internet or have them mail it to me. I stay away from luxurious accomodations because I don't see any reason to pamper myself in a nice hotel room, when I really want to just walk out in the cities and enjoy the atmosphere.