Managing an airplane for a good owner can be a great experience and lead to a lifestyle few pilots will get to enjoy. Managing an airplane for a bad owner will be downright miserable. If they don't understand why you'd be worth more than $35k managing their airplane, then I'm going to assume they've never owned a plane before or go they through crews like crazy.

Ask for a budget upfront for crew salaries, training, hangar, cleaning supplies, aircraft stock, chart/nav subscriptions, flight planning services etc...

If they haven't thought of that stuff yet, which it sounds like they haven't, tell them you'll prepare a budget for them to review. Just make sure you get paid for you time.