A good alternative, that im pretty sure will work, is to buy one of those prepaid "gift" mastercards/visa and use that on google play. I think the lowest denomination is $25(its gonna cost like an extra fee of $2) and you can get them at gas stations/dept.stores . You can spend the excess on the card anywhere that accepts credit card, so you can spend the rest normally.
Make sure to read the back of the card, it has to say it can be used online, and not just online 'in canada'. i have an old card i used successfully around somewhere, l can dig it up if needed.
hope that helps