The thing to remember is that every seller has a true bottom line.
Let's say a seller is asking $69,000 for their property and the lowest their willing to accept is $63,000.
If you weren't asking for closing costs they would agree to sales price of $63,000 but you want $2,000 in closing cost assistance so they'd want a contract for $65,000.
The thing to remember is there is no free lunch. Closing cost assistance from the Seller is factored in by the seller when their negotiating with you.
I would highly suggest you find yourself an experienced buyer broker to assist you. This won't cost you anything and will be to your benefit. I've attached a link below to one of my more popular blog posts here on Trulia on how to find a great Realtor. I hope you find the information helpful.
Good luck and happy house hunting.