After researching online the new lightning USB aftermarket chargers don't function well. Otherwise the old chargers I've gotten on amazon and eBay pretty cheap.
I've never really tried a cheap USB charger.....I'd look and see what Belkin offers. What I needed was something to consolidate the charging of iPhones, iPad, and iTouch. I found it in the Skiva PowerFlow QuadFire on Amazon. It's $20, but provides 4 USB outlets (4 amps / 20 watts), two of which will handle an iPad or other tablet. The plug prongs fold in for travel. This makes a great central charging station for the house, and frees up the chargers that came with the phones for whatever.