i cannot remember my experience very clearly, but roughly.
the expense seriously depends on your own situation.
a book: $15 (you can save it by borrowing or get if from library or read online)
registeration for G1: about $130
training class: hundreds of dollors (but you don't have to. I didn't personally)
practise driving with your coach: $40/h. usually ten hours before G2 test.
G2 test: free of charge.
if failed, you'd have to pay.
Using a car for G2 test: $80.
after G2, more practice? 10 more hours with your coach? $400.
G test: $75.
using car for G test: $80.
it cost me nearly $1000 to get a G. but i am a slow student.
good luck!