Over at newegg.com! I know it’s not the best media out there but I do know the NEC-25xx series drives burns this media fairly well or at least it did on the few test discs of Optodisc media I had. I’m not sure if this is Silver Matte / Shiny Silver top though - I really wish newegg would do a better job specifying what surface the media has otherwise they do an awesome job bringing us great deals on media.
The only other thing I’d have to add is if you’re looking for cheap media don’t neglect Amazon.com. I’ve found Ridata media there very cheap on occasions as well and that was with Free Shipping already.