runDisney medals are typically of quality design that utilize popular characters and unique themes. You can find both medals and shirts from past in-person runDisney races on the second-hand market. There are a variety of sources that runners use to sell their swag.
If you're looking for a virtual race to run and love the swag typically offered by Disney, you could make up your own virtual race using second-hand medals and shirts.
You can find a big mix of shirts and medals online. Often they are not being sold together so you might have to do some detective work to find a good set.
As expected, there are a lot of runDisney t-shirts on eBay and runDisney medals on eBay. When you expand your search to reseller sites like Poshmark and Mercari, you have a really good chance to find a pre-loved runDisney medal and a matching shirt in your size.
I found the medal and shirt from this year's WDW 5K, shown below, for sale by two separate sellers on Poshmark earlier this year.