I like DeGrom as well. He definitely fits the need. However, if he's too expensive, I'd look at Baumgarner. The Giants are an older team and it appears they might be due for a rebuild. A trade with the Giants might be attainable.
With either option, I could see trading one of the current starters (Heaney,, Skaggs, Barria) as part of the package to offset the loss of prospects. I'd imagine Barria would be the choice due to his years of control left.