In 2018, the Sega Shop online store added 6 different posters to their selection. 4 are really simple & drab, while 2 are a fun little character study.
The bottom two "Born To Run Since 91" are army drab-green with 'stencil' large printing & not much in the way of a background. Both end the sentance with a white classic Sonic face. The right-side poster has Sonic faces among the 'camo' pattern. The "flag style" posters are also pretty simple, with Sonic's name, 2 stripes, a portrait circle and "1991" between 2 stars. They're that 'weathered/stamped' look that's usually used on clothing...this time on a poster.

The colorful ones are for Sonic Mania, specifically the little fun Youtube short cartoons. Whoever is doing the art for those has their character portrait / expression test sheets printed for these two posters. The first has Knuckles heads in black/white & color, while the 2nd has Tails heads & one shot of just his spinning tails. Both types of posters are really something new for the genre of merchandise. Super plain (I guess if your room is really busy?) & then sketch-book-style mulit-shots. Whatever you feel about these, they're not 'more of the same'. Each one is about 15 dollars in the SegaShop in Summer 2018.