I'd say just hunt eBay until you find one that's the right price and condition for you. I just checked, there's a bunch right now with a $20 BIN and $20 shipping from Japan (would probably take 1 month to come in by sea because of the pandemic) but with various bits that are yellowed. If you're willing to Retr0bright it, that's not a bad price.
The original Retr0bright is for a gel or cream, and so that's what a lot of people do. David, The 8-bit Guy, uses a high strength peroxide in hot water in the sun and gets good results. He's done it a number of times
since his first video. A few times he didn't completely reverse the yellowing, but could have if he repeated the process. Doing it this way is easy (pour some peroxide in a clear tote with hot water and leave it in direct sunlight for hours, make sure the pieces don't float). You could also substitute sunlight for UV light, if you got it, which would make the process go faster (as well as not be limited to certain times of the day). Anyway, I mention Retr0bright because this is how you can score a SFC the cheapest.
AV cables, power adapters and controllers... The SFC uses the same AV cables as the NA SNES, so you're good there. As for the AC/DC power adapter, you're good with anything that would work for the model 1 Genesis. As for controllers, you can use any NA SNES controllers with the SFC. However, to match aesthetics, you might want an actual SFC controller (the SFC and PAL SNES controllers have blue, green, red and yellow buttons to match the logo while the NA SNES has the light and dark purple buttons). Just note that the official SFC controllers have short cable lengths. If you find that annoying, you can either get an extension cable or a different controller. I recommend the Cirka S91, which comes in both color schemes. They are VERY good controllers, it's all I've been using since getting one!
https://stoneagegamer.com/snes-s91-cont ... cirka.html