I have a Zoom L12 for mixing/recording my synthesizers, PC system sound and additional PC audio interface. I got it used for $500.
You can get super cheap mixers as well, but the quality will probably be hit-or-miss. (Proper grounding and interference being the biggest issues.) I got lucky with a $40 4 channel mixer that I use when running too many synths and just need to route sound somehow.
I have a Zoom L12 for mixing/recording my synthesizers, PC system sound and additional PC audio interface. I got it used for $500.
You can get super cheap mixers as well, but the quality will probably be hit-or-miss. (Proper grounding and interference being the biggest issues.) I got lucky with a $40 4 channel mixer that I use when running too many synths and just need to route sound somehow.