The answer to your question depends on the price range, condition or property, motivation of the seller, and situation of my client.
I recently submitted an offer for a client on a decent townhome in VB for $171,000, and asked for $3,000 in seller concessions with a home inspection. The seller is also installing a new roof, and new windows were also recently installed. Got that offer accepted without much problem.
However, up on the peninsula in Hampton, and against my advice, I had another client ask for $4,500 in seller concessions on a $145,000 condo in great shape - and they lost it to another buyer asking for just $1,500 in concessions.
In our local market, what we can ask for on behalf of our client depends on a lot, as each property is so uniquely different. I work with a lot of condos and townhomes priced below $225,000, so that market is entirely different than a SFR in the $300,000 price range.
Frank Biganski, Realtor ABR