Hostel go for an average of 20 to 25 euros. Some less some more. Book your hostels as soon as you can, since you know where you are going already; dont put it off. You will save alot of money that way. We booked in Berlin a month early and payed 12 eruos a night. Everyone else was paying 20 to 25 that night.
In Munich stay at Wombat Hostel. Its the best hostel in Munich. It has a bar that all the other hostels come to including Jeager and Euro Hostel. All good but Wombat is where the party is. At happy hour the bar is packed with over 100 backpackers and then everyone meets up with new people and goes to clubs.
You can buy beer at supermarkets for about 2.50 for 2 liters/6 pack. Otherwise you will pay around 4-6 euros for a single beer at bars/clubs. WXine and liguor are the same way.
You can make your food for about 2 euros a meal. Or you can buy it on the streets for about 6 euros a meal.
Supermarkets are the way to go to save money.
We are doing 30-40 euros a day, inlcuding the hostel. Buying all our food and beer at supermarkts helps alot.
In Rome we stayed at Backpacker Hostel. It was the biggest party place yet. Only 35 people stayed there but dont go ther if you dont like to party. Other good hostels in Rome are Yellow hostel; Guys Paradise; and MJ hostel.