No problem with giving appraisals here, but it is important to keep in mind that giving an accurate value is nearly impossible without looking at the unit in person. Machines like this in good shape will usually bring $1000 or so, and the better machines will bring more, but prices will vary significantly depending on tooling, vices, drill chucks, end mill holders, etc. that accompany the machine.
The previous mention that Johansson was purchased by Clausing is correct, so this is a pre-Clausing machine, but as already pointed out, there were few if any changes between the Johansson machine and the Clausing 8520/8525. It is a very robust machine for it's size and you will not regret purchasing it if the price is in the proper range.
One thing to look out for is the gears for the fine feed in the headstock. Some of the gears are brass or bronze and will strip teeth very easily. Many of these machines have that problem, but not all. Some parts are still available from Clausing, but they are very expensive.
Most of these machines came with a 1/2 HP motor if I remember correctly, and a popular upgrade is to replace the motor with a 3/4 or 1 HP motor. I've got a 1 HP on mine and I love it, nothing slows it down. These machines do not have a back gear, so it can be difficult to get slow enough for some operations, but lighter cuts and lighter feed rates can help make up the difference for those times when you cannot get the cutter speed slow enough, such as when using a boring head or a fly cutter.