>>42598645
Since Sunset Shimmer's Time to Shine establishes that Sunset is pretty good with technology (but not as good as Sci-Twi), I believe she probably got all her appliances and electrodomestics by scavenging them, scrounging and going dumpster diving for them. Then fixing and cleaning them up.

It'd explain how she got such a unique blend of old and new tech and it's a plausible way for her to afford them.

Also, she probably learned to play the guitar by asking Flash for guitar lessons as an excuse to get closer to him, only to realize she actually liked playing guitar. The first song she learned to play was all about being true to herself, "True Original" by PostCrush.