Looks like your garden-variety RG
neck pocket crack. If that's the extent of the damage, it's probably not a huge deal. This is extremely common on RG's. It looks like the finish is either "nonexistent" or is clear, so the true extent of the crack should be pretty easily seen if the seller is able to send you additional images. If the seller
can't or won't send additional images, or at the very least, won't give you more information, the I'd stay away from it. Anyway, at a glance, it doesn't look particularly serious to my admittedly untrained eyes.