I use the ziploc vacuseal bags. If you make sure the zipper is free of hop dust (I use pellets, lots of dust) and stick a piece of tape over the vacuum port after you vacuum it out, it holds the seal well. I folded the tape over to make a handle for removal and reapplication and have yet to have any problems. My hops have not changed in color, they still seem as pungent as when I got them, and my freezer doesn't smell like hops so I don't think they are letting much if any go.
Cheap, somewhat laborious solution that allows me to save money buying bulk hops without spending another $100+ on a proper vacuum sealer.