In many cases the limit to the amount of seller contributions will be governed by your lender. Maybe 1-3% of the price going towards your loan fees. If you are not getting a loan, you could ask for as much money as you want.
Lenders won't want any cash going back to you at closing. You might have to sign papers saying that there is no money "under the table" from the seller to you. All of the seller's contributions will be paid out at closing (or held for later payment).
Feb 28, 2012