You have to combine that with Award Nexus (www.awardnexus.com), which can search availability but can't determine cost (since cost varies depending on which program's miles/points you're using, and that's what Award Hacker helps you determine).

So use Award Hacker and Award Nexus together.

At Award Nexus, click "more signup options" under the green Purchase button to sign up for free (and get a certain number of searches for free) as a FlyerTalk member.

I know of no "free" site combining both functions together. So the choice is between paying (a lot?) to get it all in one place, or using two sites together to do it for free (assuming you don't exceed your free search allotment at Award Nexus).