My memory might stretch back farther, but this is the third bagged/sealed Bumpman I clearly recall on eBay. One of the other two was in a lot.
A typical year usually brings one or two loose copies to eBay, with or within lots. As with most things, timing is pretty much everything to see, let alone bid, on the listings.
In all cases, there's more than a fair chance of recirculation at play.
For this one, I figured an easy $500 - $600 given the market climate. What is got is quite a stretch, but I've seen far, far worse cases of bid inflation relative to usual pricing over the past year or two for items that are far, far, far more commonplace.