It is very interesting to find such items at Value Village. Were you on a hunt for ham radio stuff there?
Yes, that does seem pretty high priced. I think there were about $500 brand new, but I could be wrong. I know they probably are more expensive now, but nearly everything is.
If I needed a mag loop antenna, I would not be interested in it for anything more than $250, unless it came with a return guarantee of some sort. I think they were originally rated at100 watts, but I understand it is is possible to damage one by running that power on high high duty cycle modes.
Rod J