Matt,
99PM2032 would be a model 101.07300, which would be the first (babbit bearing) 12" that Atlas built for Sears in 1937. However, the lathe in the photograph isn't that model. The one in the photo has Timken bearings. You can tell that difference by looking at the right or left spindle bearing area on the headstock cast. If there are two bolts with a removable bearing cap at those locations, then it has babbit bearings. If there are no bolts, it's Timken. There are no bolts. Further, it's difficult to see because it appears to be mostly hidden by the cross feed crank. And it also appears to have been painted, whereas originally it was chrome plated. But up under the cross feed crank is a pull-out knob which when pulled out engages the power cross feed. Of the 12 Craftsman 12" machines, only the 101.07403 has that knob. And as the current owner says that the nameplate says 101.07403. that's what it appears to be. So if it is actually 36" between centers, the catalog number will end in 2078, not 2032. The characters in the catalog number to the left of the 4-digit number changed over the years but the 4-digit number did not. It first appeared in the 1940 Power Tools catalog.
The finish condition indicates that it was probably recently cleaned up and refinished. From the one small photo, it looks like it was well done. It still has the motor belt guard, which is not too common. Going prices of Atlas lathes varies widely across the country. Down here near the Gulf coast where they seldom turn up, $850 would probably be an excellent price, given the apparent condition. I'm not sure about up in PA. But what you need to do before you actually buy it is look at it up close and personal. Check the way thickness with a 0-1" outside micrometer to evaluate bed wear. The original dimension all the way across both front and rear ways was about 0.3750". If it has seen any use at all, you should be able to see where the carriage ran and where the tailstock ran. Measure the thickness where neither ran and where each ran. Make these measurements in four or five places on each way, starting near but not right at the headstock and ending down near the right end. If the difference is under 0.0020", it's OK. 2 to 4 probably OK. Over 4 you're probably looking at having the bed reground. Which is usually pretty expensive.
Note also that if there are any significant accessories (you said no steady rest), that adds to the value. And if it comes with none, you are probably looking up to another $500 in the near future to acquire them. However, starting off with a lathe as apparently clean as the one pictured is certainly a plus. At least you apparently won't need to expend any labor on the lathe itself.
