Hm...well there aren't a lot of Google results, and no good acronyms that I'm seeing, so $250 + fees might be a fair offer at the moment. But if .mobi takes off (the key word here is if), you could get more for it. No one knows what .mobi is going to do, so it's really up to you and whether or not you're willing to take the risk.
Personally, I'm holding onto my 31 LLL.mobi's and hoping for the best.