I wouldn't worry about the warranty, chances are you'll never need it, I didn't.
I'd offer them 8k for the pre reg bike. When I bought mine back in 2015 the the dealer wanted 9k, I offered 8, we met half way. If I could get a new 1050 for that I'd take his arm off.
I never got mine dealer serviced at all but still got the Suzuki recalls done and never needed any warranty work, at 36k miles now, using no oil and running well.