I am not selling add-on boards any more, but I can recommend my good friends at https://misteraddons.com/ and https://www.etsy.com/shop/zerohimself for your MiSTer needs. I will leave the info up on this page for posterity.
I’m trying to put together some practical links of boards and BOMS to make it easy to order parts for boards in medium-small quantities. This way if you just want to build your own, you can! Reference designators can be found on the linked GitHub pages, with notes on my pages. I did not include OSHPark links when the pricing was not practical.
Access the different Addon boards from the top menu or here:
Here are all of the BOMS from the various pages in .csv format:
Here’s a BOM I have used to order in the past; it is deprecated so use as a reference only.
Not included is the 40 pin right angle connector for the SDRAM board (couldn’t find on LCSC), a fan, and various short male headers.