SCR Merchandise (more commonly known as merch) is merchandise/clothing for Roblox Avatars that are offered for sums of 10, 15 or 20 R$ (ROBUX). The first 'wave' was released on December 22nd, 2018 with 4 T-Shirt models available for sale. And a second wave on 24th of July 2019 with 2 T-shirt models.
SCR Merchandise can be bought on the official group's 'Store' tab or from the stores around the map.
Here is the link: https://web.roblox.com/my/groups.aspx?gid=3620943
Real-Life Merchandise
After the 5m Update, BanTech announced real life merchandise on Discord and Twitter, The link can be found at https://teespring.com/stores/stepford-county-railway