You can buy new discs on Amazon. While there are many minidisc players on eBay, my best finds are on Craigslist. Why? Demographics. The old guys who find them in a shoebox in their closet think they might be worth $20. I’m not exaggerating- I travel a bit and in large or small towns I’ll scan local CR for “minidisc”, “mini disc”, “minidisk”, etc. I recently acquired five players from a single seller in Bend, OR for $50. All in nearly pristine condition.
I buy empty minidisc clear cases from Japan (similar to CD jewel cases) on eBay. I have a photoshop template for printing card stock on my Epson that allows me to create art and graphics that fits perfectly in the case. Once the completed minidisc is placed inside it fits like a glove. I find it all very satisfying.
I also bought a Sony MXD-D3 ( hard to find and expensive on eBay) so I can quickly rip an entire CD. Or I can use the “Rec-it” button and just capture a single track.
One of my other decks is a Tascam MD-301 MK II which has a keyboard port so I can easily tag albums and tracks with text that dances across the player screen on most playback devices.