Dude if you get -27 for +300 let me know where. I'd be on that like flies on garbage! Right now i can buy up to 26.5 and get +167 at Heritage
Buying up and down always ends up equating to less then it would be on an Alternate Line, it's just the way things go. For example, on 5dimes go to a big favourite of about 14, I'll use the NC State game as an example. They are 13.5 point favourites and -515 on the ML, but when you go to buy it down 9.5 points to -4 and that cost -540, more than the ML. Bring it down to a PK, and they're charging a staggering -1240. So be aware of this in the future and try to snag Alternate Lines rather then buying/selling.