If your going to use a transcoder, you can stick to Euro SCARTs, which are usually quite cheap and easy to get.
My TV takes pure RGB input but needs Japanese 21pin cables, which are typically harder to get and more
expensive.
Being in Japan, I've slowly been building these up over time. The Saturn cables, can go for over a $100
online, but I found mine for $20 in a shop. The PS1 cable is cheap, but kinda redundant, as the PS2 can output
RGB through component cables anyways. SFC cables are very cheap, but most of them have leaky capacitors
which must be replaced or they won't work properly.