M-Disc prices have skyrocketed over the last year : r/DataHoarder
Amazon.com: Asus 16x External Blu-ray Drive with BD Suite Disc, USB 3.0 Cable, Power Adapter and Cord (BW-16D1X-U) Bundle with 50GB Verbatim M-DISC BD-R DL : Everything Else
Mic-UK: M Disc for archival durability. Tests and review.
PRODUPLICATOR ODD-PIONEER-XD07S-BD050 Pioneer BDR-XD07S Portable 6X Blu-ray Burner External Drive Bundle with 50GB M-DISC BD-R DL and USB Cable - Burns CD DVD BD DL B
Buy Blu-Ray Disc Media Dual Layer 50GB Disc at TapeandMedia.com
Verbatim M-Disc Lifetime Archival BD-R DL 50GB 6x Inkjet Printable Spindle (Pack of 10) 43847 from Codex Office Solutions
Amazon.com: LG BP60NB10 Portable 6X Ultra HD 4K Blu-ray Burner External Drive with CyberLink Software, 50GB M-DISC BD-R DL, and USB Cable - Burns CD DVD BD DL BDXL Discs : Everything