First off, that is not the correct model number for that machine. If it is, as it appears to be, a 12x36 (bed LOA is 54"), the model number is probably 101.27440 made between 1950 and mid-1957. Or it could be a 101.07403 with a 54" bed (so still a 12x36) with the QCGB kit installed. If the latter, squirreled away somewhere may be a stack of 10 to 15 loose change gears. If it is a 101.27440 it was made between 1950 and mid 1957. If it started life as a 101.07403, then it could be as old as 1940 or as new as 1957 with the QCGB made between 1950 and up into the 1970's or 1980's. I'm not sure just when they quit making the GB. The drum switch is hiding the front of the headstock so I can't tell whether the headstock is the early type with an oval hole or a late type with a rectangular hole in the front of the headstock casting for the original motor switch.
If it started life as a 101.07403, it may have the original serial number and some letters stamped into the top right end of the front way and the model number stamped on a name plate on the rear of the bed. Or both serial number and original model number stamped into a plate riveted to the right end of the bed.
Whether it is an original 101.27440 or was originally a 101,07403 doesn't much matter except that if the latter it could be up to a decade older and could have more wear on the bed and lead screw if it was originally sold as a 101.07403 or could have been made as late as 1957 regardless of which it originally was.
In any case, the presence of the QCGB is a definite plus. However, $1800 may be a bit much unless it has a few more accessories than you listed.
Having the AXA QCTP is a plus, especially if he has a good assortment of tool holders. But I would offer him $1200 cash and unless the bed and lead screw are badly worn, take whatever he counters with.
To evaluate bed wear, with a 0-1 micrometer measure the thickness of the front way near the right bearing (for the original thickness) and 6" to 12" from the face of the three jaw chuck. To evaluate lead screw wear, compare the thread width right next to the right bearing to that near the headstock.
Anyway, post the serial number and correct model number.