Here in the UK you can expect to pay around £25-35 (that's about $35-45 I think).
You probably don't want to pay much less than that because god knows what kinda money-saving tricks the studio might be using to keep the prices lower than that..
If you want to avoid wasting money, say no to any of those bacterial soaps or other products they might try and sell you for aftercare.
Good old fashioned hot water and sea salt mixture will do the trick instead. Wash regular, pat it dry and keep it clean and you'll be fine.