I just ran across a deal at Amazon. There is a twin set of Farberware muffin pans (a 12 and 6), silverstone. The set is on closeout for $6.60, already a bargain. But there is a $5 mail in rebate on top of that. Shipping would make it a less good deal, but if you have prime or other things to qualify for free shipping, it's pretty nice.

It has to be ordered by JULY 30. The item name is SilverStone Simply Baking Muffin Pans, Set of 2. I haven't done mail in rebates through Amazon, but presume they work fine.