Don't try to go too thin, you'll regret it later. If you can't afford anything close to this: Save more money or go for less time.
Airfare
$400 - $1200 depending on time of year
Call a few good agents, if you're flexible, fly charters, look into open jaw tickets
Rail
An 8 hour train ride will cost an average of $100 - $125, this can varystrongly by county.
Daily Money
C$100 per day will get you a cheap hotel or a hostel, all meals, a few sights, drinks if you want, a handful of extras that WILL come up.
Before You Leave
Don't forget:
Backpack (duh!)
Insurance
Visas
clothes
toiletries
good shoes
Bottom Line
About C$900 per week plus Airfare
All of my trips have been very close to this. If you will be alone, add a bit. If you will be in a large group, shave a bit off.
The old, yet very true, rule is:
"get toghether everything you think you will need, then take half the luggage and twice the money"
now twice the money will never hurt you but let's be realistic here. Half the luggage, thats realistic.
Here is am example of an experienced travellers backpack for a trip to Europe between May and Mid-October:
1 pair or khakis or cargo pants
1 pair of jeans
4 T Shirts
1 pair of shorts
1 sweater (doubles as semi dress up shirt)
5-7 pairs of under wear and socks
1 pair of sandals
1 pair of multi-purpose shoes
Toilet kit (don't get carried away)
Ziploc bags
2 large garbage bags (multi-purpose)
A discman/mp2/minidisc is great
several dryer sheets (help your clothes smell reasonably fresh even when they're not!)
Saftey pins, matches, a sewing kit
A padlock
A journal + pens
1 good guide book
Duct tape (repairs and hey, it's very multi purpose)
Make a list of all the places you have researched and still want to go to (having heard of a city is not a good reason by itself to go there).
Put all these places on a map
Find a logical order taking possible night trains into account
Don't try to see too much, you won't see anything. I advise being as flexible on when to leave a city as possible. You can't know where that great surprise will be hiding.
Don't underestimate how much fun a good hostel can be. I don't usually stay long if there is no fun at night. Some of my best memories are sitting in common rooms with new friends.
For trian schedules: www.bahn.de