hey i was there thsi past summer for 10 weeks i satyed with a friend in rome and in austria i sepent total about 5000 for 2 months…for me i seemed to spend more where i stayed for free… thats was just dumb of me!

Keep in mind a lot of things cost less if you have more people with you. I definitely spent more money when I was by myself (whether this was due to neccesity or lonely traveller syndrome can be debated []). But seriously… food is the biggie. If it’s you and your buddy, and neither of you are gigantic, your food bill just automatically split in half. I think I literally spent 3x as much money by myself on food than I did when I was with a friend, just cuz you’re more likely to be hitting up street vendors and shit than making your own vittles.
 
Anyway, I’d say if you’re thrifty, you can expect something like… maybe 2 grand each after airfaire and trains. No matter what you do, hostels will set you back approx 30 bucks each per day. Since you’re going in December, there’s really nothing you can do about that. If you can stay places with free breakfasts, eat fruit for lunch, and then make your own pasta or something for dinner, food is like 5 bucks each per day [] 
 
Oh and keep track of your expenses. That’s the best way to make sure you don’t go overboard, keep a little notebook and write down all the money you spend. Sounds anal, but trust me, you’ll thank yourself for the peace of mind!