Signing Hiller is the idea I like the best, out of all the suggestions I have read.
Considering Ramo is making 2.75 million; and will be the starter on opening night, I don't see Calgary going the Hiller route honestly since he'll cost quite a bit more (~4 million) and I don't think he'd be happy playing split duties on a Calgary team.
I think there are three goalies Calgary should probably target:
Reimer, Dubnyk and Greiss.
All three of them are younger goalies with varying degrees of NHL experience. Reimer would probably cost a draft pick, probably along the lines of a third rounder or even the second rounder we got from the Avs. He's the only one that would require give up extra assets.
Dubnyk has had a rough year. A really rough year. Calgary could definitely give this guy a good shot to be considered a legitimate NHL type goalie. Might be the only team with the luxury of being able to take this shot at him.
Greiss is just kind of a safe backup. He's quite solid, will play his limited games and not complain; and just a goalie that doesn't hurt your team when he's in.
The goalie in Calgary shouldn't cost this team more than 2 million dollars, have to make sure Ramo knows he's the guy, but also need healthy competition.