Here are 2 small size pin buttons. They're only about the size of a quarter. These are available in Hot Topic in 2015, but they will be in 'the pin bowl' a display bowl filled with small pins from many different brands.
Each pin is classic styled, the first with forward-facing Sonic face & no outline, while the 2nd is more complex. It uses neo-classic art for both Sonic & Tails. There's jumping-pointing Tails and running profile Sonic on a gray scattered checker background. These pins are 2.99 , which is extreme over-pricing as they're quite tiny and extremely simple for companies to produce. (The mark-up here is huge, look for a sale) With mark-ups like this, it isn't any wonder that fakers step in by cloning or producing their own pins.