MOD EDIT (no naming of rom sites) has ips files that you can apply to your own roms, so I'm pretty sure it's not against the rules for me to post that link.
There are other places you can find pre-patched roms, but that's definitely a no-no.
Emulation is the easiest way to play them. You can also load a lot of them on various Everdrives if you want to play on legit hardware (not all, some use tricks of the emulators which don't exist in real hardware, another reason why emulation isn't quite perfect, but a large number). Some of the more popular ones are made into real dedicated carts by repro makers and can be found on various websites including ebay (which I wouldn't recommend, for the most part the prices on ebay are more expensive than the ones on repro maker sites -- again, some exceptions, I know certain people who own sites also list on ebay, but as a rulee)