Thank you for your question.
There is no set price when dealing with attorneys. For contract reviews, most attorneys will require an hourly fee. Thus, the amount it ends up costing you will be a function of how many pages the contract has, whether there are other documents which must be reviewed in addition to the contract itself, and whether you are asking for any rewrite or negotiation of the contract for you by the attorney.
A simple 5-10 page document can cost anywhere from $300 to $1000 to review in attorneys fees.
That being said, there are many attorneys right now that would agree to do a set price for the review. You could offer a flat fee and see if someone would be willing to take it.
The prices are going to very between big firm and small firms and experience level of attorney. I've been doing commercial law for 11 years and my price is $350 per hour. However, I know senior attorneys who have overwhelming experience in contract negotiation that charge $850 per hour. So, it depends on the level of service you want and the complexity of the legal issues involved.
Let me know if you want to talk more about this or have other information that you want me to address.