What would you pay for a truck with 113k +miles?

My friend is selling his truck it is a 2005 Ford f-250 super duty (I think) it's a huge truck (diesel) with a lift kit. When I said I'd buy it he said he would throw me a deal, he said it blue booked for 18k and that he would give it to me for 15k he said it has had a ton of problems but he bought all new parts also it has 113k +miles I feel like 15k is to much for that maybe I'm mistaken but I'm sire I could go but a new car with that much.

I would not buy it. If it has a ton of problems, it is bound to have more.

Never buy a vehicle that the owner says "has had tons of problems with"it. There are a lot of good cars new and used that you can buy for $15,000. I think you need to look around more before deciding.