Need reviews on the charging cases for Apple iPhone 5c on eBay! Are the cheap ones worth it?

I'm looking to buy a charger case for my phone. I'm a highschool student that can't spend $70 for a nice one. I have one in particular that I found and it's gold. My question is, is it worh spending $15 for a case if it won't even work after a few charges

I've found with lithium batteries that the cheapest just aren't worth it. If they work they don't work very long. At the same time premium or OEM batteries are just overpriced.

I go middle of the road. I don't get the cheapest or the "premium" brands. I go with the third parties with a good reputation. Based on that Alpatronix makes a case with very good reviews for $34 on Amazon. The $15 cases have garbage reviews.