Just a few tips. Spend the most money on the most permanent stuff and that which affects the sound in the room–monitors, treatment. Of course better converters are better but even a midline MOTU box is better quality than professionals were using not that long ago. I use a Mac and Live and love it but if I was going budget and not planing to be mobile, a PC desktop running Reaper and lots of free awesome plugs would be fine, especially if most of my music-making was in hardware. Cables, patch bay, hardware effects, all of that will outlast the computer and software.

For monitors, be sure to try them out with music you know.

Also, I’m not a big believer in analog summing, so trust your ears and judgment. Don’t buy without trying. For me, a good mastering engineer after I get done with it makes the biggest difference.

HTH.