1. On the top of the list would be used Shure SM57 and SM58 microphones. These are an industry standard and very inexpensive. You can pick up used ones in decent condition for 20-50 bucks each.
2. Next on the list would be FREE plugins. There are so many good ones that cost NOTHING. Check out REVERB.com free plugins (there are other sites as well).
3. Don't skimp on the accessories - cheap things like guitar polish, finger-ease, a new fingerslide or capo, a new guitar strap, music stand. Sometimes the little stuff makes life better but the musician in your life is always focused on the 'bigger' stuff.

Most of these things will fit in a stocking!

Peace,
TC


If it has strings I will find a way to play it!

You can hear my tunes at https://soundcloud.com/tc-gypsy