Yes, you can check them out on ebay, Amazon etc. It requires a replacement back that should come with the charging unit. Make sure you get one specific to the S4
I found several and none of them needed a different back. The receiver antennae is so thin, you can barely notice the bulge. I had to replace two phones because constantly plugging and unplugging the charger cable eventually loosened the plug and they had to replace it. With the wireless charger - no more. One word of caution. Don't leave it on the charger beyond when it's fully charged. You might risk blowing up the battery.
When I get home from work, I put it on the charger until it's back up to 100% and then take it off.