Yesterday I purchased a Joy-Con controller ($94), Super Mario Maker 2 ($65.99), and Super Mario Party ($64) and after applying the 15% off discount code paid just $190.39. You must purchase at least $120 worth of games and accessories to obtain the discount.
The Joy-Con controller and Super Mario Party were both purchased through Catch's eBay Store. There are a number of other games available in the store at great prices and at an extra 15% off will be cheaper than anywhere else on the market.
Other notable games available include The Legend of Zelda: Breath of the Wild ($69), and Super Smash Bros ($68).
I also found a seller, frugal-shop, with a number of Switch games for sale at a good price, plus when you buy two or more you save an extra $8. This stacks with the 15% off code.
Their games include Super Mario Party ($69), Super Mario Kart 8 ($69), Pokemon Let's Go Eevee ($64) and Pikachu ($69).
The link to these stores doesn't work properly if you have the ebay app installed on your phone. Uninstall the app temporarily and the links will work.