If I had Halladay, I would want more than that. But, if he's wanting saves, this might not be too bad. I still think it's underpaying.
If I was going to trade Halladay for three, and I only had one closer, I would push for one SP to replace Halladay plus two closers to solidify my saves.
So, I'd offer Hellickson (potentially very good) + Crow (iffy on keeping the job) + one established closer for Halladay.
If he takes the deal you have on the table, laugh yourself silly.

But if he doesn't, it might take 2 closers. If he's smart, that's what he'll push for.
Help on mine?