$30 or $35 to the
right person, IMHO
Not a lot of people (well, at least not anywhere around here) use the term "lotto". They say "lottery", Im not sure what's its like everywhere else, but those are the people that are going to be typing it in.
Because of my locality, I would give it $30-35 because no one around here says "lotto" and plain old "lottery" is more common.
Also, LotteryForum.com and LottoForum.com are the only extensions registered, no one has taken Org/Net/Us/Info, etc. Therefore it doesn't seem to be in high demand too much.
Bah, I dunno man, that's just my honest opinion.
Good luck with your domain