My personal experience with "retro replacements" is: DON'T!

Get a good power supply - e.g. for a notebook or netbook - which delivers the correct voltage and just solder the proper plug on to it. E.g. the one for the Asus EEE PC700/PC701 (9.5V/2.3A) . Power plugs are (mostly) standardised and still readily available, so no problem there.

Since most consoles of the 80s and early 90s use the same voltage (9-12V), the ORIGINAL power supply for the Sony PS One/PS2 Slim is a great candidate btw! Especially since its power plug is identical to the one for the Sega Genesis Model 2 and Sega CD Model 2 - and the latter Game Gear-revision.