I agree with Mr Rakesh, But if the project is not approved by any national govt bank then there are various documents you should check with builder before making your decision i.e.: 1. Registry of Land. 2. Documents from Bank to check whether project is bankable or not. 3. NOC from local development authority. 4. Copy of Buyer-Seller agreement. 5. Map of the project which should be accepted and approved by authority. 6. If possible, get documents which can display that more investors have shown their trust in the project. May be this can help you in making your further decision.
Check the papers of the Land with residential and commercial purpose. Some times there is NA letter for only the residential purpose and not for commercial purpose but builders never take any permission.