we get it. building your own lil machine can be satisfying and cool, is more general purpose THE POSSIBILITIES R ENDLESS. but what are the practicalities?
SNES Classic: roms installed and tested with better (read: accurate) emulation than any other emulation available, built and housed w nice a e s t h e t i c s, 2 controllers - $140
NZD not USD:
RPi Model A+ (equiv-ish to nes mini spec) - $45
2x Generico USB SNES controllers - minimum $40
microsd card - $10
nice-ish case $20
5 - 10 hours at least getting everything setup depending on how nitpicky you are about having a nice to use setup: order components, put together hardware, dl, install and configure loads of shit (OS, drivers, emulators, roms, patches), develop custom settings for each rom, package roms up with custom settings, have different games running on different emus coz zsnes won't work well for everything and you will possibly encounter game breaking bugs at points in the game anyway, but you can also get the maybe better versions of games e.g. GBA FFVI patched with SNES sound (probably not worth it for slightly better translation/additional post-game)..... etc.
tl;dr the RPi is a bitch to set-up and even with a bunch of time spent getting things working as accurately as possible your experience will not be as true to the original as buying this, plugging and playing.