I sell a lot of prints. I sell 8x10 and 8x8 prints that I print myself with a regular Epson printer and package in “Showpacks” which are Mats enclosed in plastic. I have painted a fair number of Christmas characters and art parodies that lend themselves well to prints. I don’t think that size print would work well with landscapes or still life.
I sell them for $25 and I think the all-in cost for the matting, ink, etc is probably around $8 or so.
I have had people ask about larger prints of landscapes but the one-off cost of having those done by a print service was rather ridiculous.