There a few ways to get started..

1) get the original WoW which goes for like RM80 if u look hard enough. You will need a reload card to create an acc (not sure if u could upgrade from 10 day free trial but its possible i think)

2) DL the WoW from internet, use 10 day free trial and then buy a cd-key from somewhere which is cheaper than buying the entire game set.

3) If u got some friends who plays WoW, they might still have some free trial cdkeys with them, u can borrow their game cds to install then use tht cdkey to make an account. If u wish to upgrade to a full account then all u need to do is reload ur account after that. ( The drawback is u need a CC to make an acount with the free trial cdkey. U cant make 1 with a reload card)

4) Forget abt TBC for now since u are just starting out. The TBC features only the 2 new races and the Outland map which is for 60-70 players. Also do take note that TBC is an expansion pack and u will still need the old WoW to play it.