I would take the offer. I would then use the 185+ dollars of profit to register about 64 of the .info domains I've been wanting to register. Then park them all at something like domainhop and hopefully get clicks.
Have you gotten any OTHER offers on the name? Casino lemon is good, but I don't think it could be branded by a company. When I think of lemon, I think of lemon cars, ie stolen, flooded, melted cars. Could be referring to the lemons on some slot machines. But that's a little too much of a stretch for me, especially since there's a lot more to casinos than slot machines.
So, once again, I personally would take the offer. We'll see what everyone else says.
:azt