I doubt you'll sell this quickly (unless you are very lucky and right end user happens by). You need to get it out there, on Sedo and Godaddy as "make offer" and Brandbucket.
Also I agree that one M would be better, as "gamer" is one M so you haven't actually shortened it, just swapped the "E" for an "M". That said, "gamer.com" and "gamr.com" are likely long gone so yours is a new chance for people.
I think it's worth high 3 to low 4 figures
generally, but there's a fair chance of an end user wanting this for a games/gamer etc related project.
Good luck
Additionally, the logo is not ideal as the last "M" looks like an "E", and "gamer.com" is a different ball game altogether

I know end user could do this too, so is promotional etc, but also might look like you're trying to mislead people and are selling "gamer.com", and that can stop a potential sale or contact in it's tracks