Can I use a Walmart iPhone 5c charger instead of the original one
When buying an iPhone charger what you want to look for is the lightning cable (the one for your 5C) having a MFI-Certification, this means that it is certified by Apple to work (most likely). These may be more expensive but are better than the .99 gas station chargers. It may still work for a while buy there is a fairly high chance it won't or it will die after just a few weeks. Your best bet is a more expensive one from a place like Amazon or one sold at an actual Apple store.

To answer your question, cheap chargers are not nearly as good and could not end up working.