Are Low Mileage Older Vehicles Worth A Premium Price? Do they need work even though they've been mostly sitting?

I have been looking for an older, lower mileage (Less than 75k miles) big SUV capable of towing for a while. Something like a 8-10 year Expedition, Tahoe, Suburban, Sequoia. A lot of retirees in FLorida have them just for snowbird migrations. I'd imagine they'd be cheap(er) as banks won't load on vehicles beyond a certain age. But I'm finding dealers and people asking a lot for them... much more than a bank would loan if one were to finance it. 

I find the occasional one owner vehicle in great condition, but the price is very high. I want to pay cash, but I don't want to pay more than what I believe I could sell it for. These vehicles sit for sale forever even after I make what I believe is a fair offer. A few examples include a 2009 Ford Expedition Limited 2WD One owner 48k miles for $16k and a 2012 Ford Expedition Limited 4WD One owner 54k miles for $27k (Seems crazy to me). The 2009 is very nice... but it's still 14 tears old and a bank won't loan on it. I was thinking $10-$12k would be more in line. ???

An older, low mileage vehicle is nice as they're usually very clean and not all rusted up... easier to work on. I wrench on vehicles all the time as a hobby (necessity). But mine are all older with matching higher miles.

I assume that all rubber and plastic degrades over time. Sitting or running, lines, hoses are said to degrade. At some point they'll have to be replaced. Obviolsy a rusty truck with 200k miles will need lines replaced a lot sooner than a newer looking (Still older) one with 50k miles. Am I wrong in my thinking that older vehicles (Even though low mileage) still need work? I think of stuff like transmission cooler lines. I've seen plastic intake manifolds just crack from being old.

What are people's thoughts?