I've used Plantskydd for years for moose control in my yard. LOVE the stuff! Pricey, but worth it. Since moose were my initial reason for purchasing it, I never picked up on the fact it's suggested for voles, which just arrived in my neighborhood last year. I'll be trying it in a lot more specific areas around my gardens this year.
Angie...There are a lot more formulations available now and it is not as difficult to find as in the past. Should be able to get it at Walmart (best price), Home Depot, and all of our local nurseries/greenhouses carry it. If we have it up here, shouldn't be hard to find in the Lower 48.