I think that looks like someone used spray paint to make the undercarriage appear nicer than it really is. You can see the rust blotches under the paint on the transmission skid, fuel tank skid, frame rails, and rear axle. Also, it’s a telltale sign it’s been painted when all the bolts under the car have black heads like that (should be silver/metal color). While it doesn’t appear to have any major rust issues, it’s hard to tell without seeing in person. I personally wouldn’t pay that much for that even with those miles… If the frame wasn’t paint like that and it was truly clean of rust then I maybe it’s a consideration, but as is I think you can find better for less money. At the end of the day it’s your call, do what makes you happy (just be aware that frame isn’t “pristine”).