it is better to seek legal advice 

2) builder is reluctant to incorporate changes suggested 

3) legal fees vary depending upon lawyer engaged by you 

It's completely upto you 

The agreement for sale draft has to be in conformity with the model form of agreement as given in Rera

However the draft can be modified on case to case basis such that any such changes should not be inconsistent with the model format or with the Act and rules framed thereunder 

Also some clauses in the draft would be completely contractual between the parties for which the model format would not apply 

So as a purchaser you have to check whether or not all the representations made by the builder to you are properly captured and recorded in the draft agreement 

Some builders are rigid and if any changes are made they refuse to accept them by saying that the agreement draft is a standard draft and no changes made by individual purchasers would be entertained 

As regards the fees for vetting the document, every lawyer has his or her own scale of fees. Nothing is standard or in a straight jacket formula. 

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The draft agreement or sale deed is obtained only to refer to an expert lawyer in the local to get his/her opinion to the genuineness of the property and if the consultant opines and recommends any change or modification, and if they are found to be genuine, then the builder has to allow the changes unless it is contrary to the agreement conditions. 

For charges, you can get to know from the consultant you have chosen for the purpose.  

Dear Client,

Indeed, seek legal advice on the "Agreement for Sale" even though the builder is reputed and the project is RERA-registered. The legal scrutiny will provide you with an agreement that takes care of your interest coupled with presentation of a compliant agreement with RERA guidelines. If the change suggestions of the builder are reasonable or mandatorily required in law, his lawyer is sure to accept changes suggested.

The cost to consult an attorney about this type of agreement can vary with the complexity of the procedure and experience with the lawyer, but it usually falls in the range of ₹15,000 to ₹50,000 in Mumbai.

Thank you.Hope this answers your query.

- Legally, you have right to check and amend the sale agreement drat , and hence you should take help from a local lawyer for the same. 

- After the registration of the agreement , it is very difficult to rectified the mistakes and even the contents of the agreement cannot be changed. 

- Lawyer fees depends upon the person to whom you will engage , however it will be very less. 

If there is any clause which is detrimental to you then you can suggest change 

Yes you appoint your side advocate to verify draft agreement and you can do require changes. While drafting such agreements anybody can write that drafted agreement is as per Rera guidelines, thoes facts are really drafted as per Rera guidelines or not are always should get verified by appointing personal advocate to avoid further consequences.

In Mumbai as per the property valuation advocates charging fees.

Minimum charges for verifying draft agreement are being Rs. 15,000 to 20,000/_.