Don't know that .22lr and .17HMR really can be compared, I think they're very different "animals" so to speak. I love .22lr, probably my favorite caliber...but it lacks the killing power, range, and accuracy of .17 HMR. If I read anything to the contrary, I think I'd question the amount of experience they have with these 2 calibers. (leaving out match-grade rifles/ammo. where accuracy is concerned, but they aren't meant for, nor used for hunting)
So, I'll avoid the temptation to comment on the "cost of .17HMR" aspect of this, because I think it's laughable. The caliber is WAY more effective on gophers than .22lr, and at greater ranges and YES, at a higher cost. It's your call. You likely won't have any get back to their holes having been hit by a .17grain V-Max round. The same can't be said about .22lr, unless you can get a head shot every time.
There is economy in .22lr, and if you have a CRAP-load of them to shoot, you shoot allot, and economy is a deal-breaker, .22lr might be your best choice. If you're a weekend hunter with a little breathing room in your budget for ammo., I think you'll really appreciate the terminal effect of HMR on small targets like gophers.
Good luck with whatever you choose, and have fun!