For a cheap solution, I'd go with a 34 cog, but you might not like that big jump to the easy gear.
I had a similar situation with my Luna. I originally had a double--don't remember the up front gearing, I guess standard 42-52 or something like that--but 11-23 cassette (for some reason, don't ask me why). Well, that certainly wasn't going to do me much good, and I became acutely award of that while visiting my brother in Asheville and riding with him. Yikes.
I got a new cassette, 12x27. Not good enough.
I called around about compact double vs. triple, and the triple would cost alot more because it involved the derailleurs. I paid $300 to have a bike shop install a compact double, and it's been great. I kept the 12x27 in the rear, but the up front change is fine for the riding I do. Got me up Skyline Drive on the Blue Ridge Parkway, and that's as much as I expect to do with my bike. No Alps or Rockies for me.
Good luck and let us know what you decide on.
I have an 11-32 10 speed IRD cassette that's Shimano compatible. Since I have a compact double with a triple front derailleur, I didn't need a MTB rear derailleur.
http://www.interlocracing.com/cassettes_steel.html
I have this on my road bike. Sorry I don't know if it will work on your cross bike or not, but worth checking out as an option.