Appraisal Came in Under Asking Repairs Needed

My wife and I are buying our first home. We're putting 10% down with and FHA loan on a house we love in the perfect area. The asking was $510k we got our offer accepted for over asking $513k. The seller bout the home in November for $456k all cash apparently and is being relocated for work. He didn't do any repairs or renovations and is selling as-is. Inspections were done last week and my inspector found many issues mainly the roof is in bad shape he found a lot of evidence of leaking and sounds like it needs to be replaced. I'm having a roof inspection and plumbing video inspection done this Thursday.

Appraisal came in under asking at $505k. Other than the roof there are issues with electrical, plumbing, the pool equipment is pretty much shot. I'm not afraid of the repairs I'm handy and can do much of it myself to save money. I'm thinking of writing a letter to the seller revising our offer to $485k and asking for a $10k credit for repairs. My realtor seems to think this is too low.

Based on all the repairs and him purchasing the home for $456 6 months ago and not touching it seems reasonable starting place to me with all the repairs that are needed.