I'm a BIG fan of the Massey 150. I'll always believe it was/is the best all around utility tractor ever built.
But..... They're getting along in the years now. What was once the gold standard as far as fuel efficiency, the handiest tractor I've ever operated, and the best buy in it's size back in the day, may have a few issues.
If the oil stain on the ground is from the tractor, it's in a spot where the oil PROBABLY came from the weep holes under the bell housing. If it's engine oil, odds are it's the rear gaskets for the oil pan that is leaking. Rear main seals leaking is almost unheard of on that model Perkins. Pan gaskets leak quite frequently. AGCO/MF offers a replacement gasket set that, if installed correctly, ends that problem. If it's tranny oil, you may have a leaking input shaft seal, OR, if the tractor is equipped with MultiPower, there's several leak points. Probably 9 out of 10 Perkins 3-cylinders have a SLIGHT leak from the engine. So long as it's only a drop or 2 after a few hours of run time, no biggy. If you see significant oil leaking, it's time to drop the oil pan.
Looks like it has aftermarket rear rims (w/wide tires) It looks like a driving range or a batting cage in the background. Probably led a life as a "turf tractor".
I see the grill is missing, lights missing from fenders (both front and rear)
A nice 150 will sell for as much as $6500 here. Average price is around $5000. $4000 is either a bargain or a rough tractor here.
"Going rate" for hauling a tractor here is about $2 a loaded mile, so expect a price in excess of $1000 for delivery.
Myself? I'd look locally to avoid the haul bill.