Insulet sent me a 3 month supply of OmniPods that I can't return and don't need and now I'm out $1,000

I switched to the Tandem T:Slim X2 and accidentally left auto-fulfill turned on on myomnipod.com. As a result, Insulet sent me a 3 month supply of OmniPod pods, and they are refusing to allow me to return them for a refund. They only refund if it was an error on their part. Since I left auto-fulfill turned on, it's my fault. I now owe around $1,000 to Insulet. Anyone else run into this crap with them? Are there any market places I can sell these to recoup some of the cost since they won't refund it?