I prefer the gravity cup, so it wouldn't be for me. If its unused it strikes me as odd that the handle is off, so either there isn't one, or it has been used and that is how the person likes to paint. Looks like they have pulled the needle back, could be to protect it, but maybe its damaged. If it is unused, then the seller cant vouch for how it performs, and they haven't said why they don't want it. These all raise questions for me, having said that $40 is cheap, if you are prepared for the possibility that it may need parts, and factor in how much that would be it could be worth it. If it is unused and like new as stated then def worth it as long as it wasn't a reject or something to start with.
Its a $40 gamble that could pay off, so it really depends on whether you are willing to risk it.