Update: The seller that has them for $4 might be iffy, so best to buy them from Amazon.com directly for $7, which is a pretty good price, historically.
Get a better grip on your phone with one these expandable PopSockets. These Amazon bestsellers are just $4 today, down from their usual $8, and they double as kickstands, which can then be collapsed down so your phone will still fit nicely in your pocket. Although these are offered in a million different colors, just the black is on sale today.