I don't have any suggestions about feeding, but do yourself a favor and buy mice from an independent source, either a reptile shop or mom n pop pet store might have frozen on hand, or Craigslist if it's not too sketchy lol. Those petsmart mice work in a pinch, but they straight up ROB you. Not sure on your prices, but mine sells em for $12ish. Reptile shop is 1.25 each. You'll have enough for a good Tstat in a few weeks in what you'll save on feed lol.