Linksys RT31P2 power issues

We have had Voipo for 3 years and it looks like our router is having an issue with the power source. Contacted support and they said we have to pay $50 for a new one plus shipping. That seems like an awfully steep price to pay for a new one when it is their device that is failing. Is is possible to buy one elsewhere and use it on this service?

We only have 1 year of our contract left and while I like the price, etc, there are many times people can't hear us or we can't hear them. luckily most people call us on our cell phones but it does get annoying when there are issues.