You can buy the hook at any number, you can't buy points though.
I know, they suck. I'd be at 5 dimes but I can't deposit to them (no CC deposits allowed in my state, M o n e y Gram flagged my attempted P2P due to federal regulations, still have no idea how they knew i was attempting to fund an offshore account)...
Hey i use Bovada as well. Just make your wager. Then click REVIEW BET. Then the next little screen will show at the top weather you want to buy the hook or not.
It's like Xerxes says....say Colorado State is +16.5 (using a hypothetical example). Type in your wager amount and hit REVIEW BET. A box will show up that says "Buy Points", open the pull-down menu and you'll see "Colorado State +17 (-120)".
Unfortunately, that's about it in terms of point buying options through Bovada. Fortunately for myself, I never buy points in the 1st place as it doesn't match my philosophy but it's just another factor in why Bovada sucks. I'm more concerned with the fact that they don't place College Basketball lines until Noon eastern time, after the opening lines have been adjusted