I don't think there's much to say about this kind of dealerships: they mostly buy cars off auctions (Manheim/Adessa/EVO/etc.) and sell to the publich with a profit (if lucky). Nothing more. So you can score a good buy if the dealer was smart to buy a good car for less and didn't put much of a profit margin, or it can be a rip off if they bought a lower-grade vehicle and jacked-up the margin. For this particular one, you can ask for a copy on inspection report that is done for every vehicle sold on Manheim, or do you own inspection.

P.S. I wouldn't call 20K/year a high mileage - if you commute in a large metro area, it's rather typical and mostly involves highway miles. YMMV, obviously...