For new grips you can look at VZ, LOK or Stoner CNC. Those are basically G10 grips.
If you want wooden grips I found the site listed below. Do a google search and you'll get plenty of places to research.
It may be too late to help you, but in case this could benefit someone, I'll comment. Another source of thin grips is Springfield Armory itself. I like the Ronin thin grips, and ordered from Springfield and placed them on my Range Officer. Several other Springfield 1911s come with thin grips, so there may additional options. Keep in mind through, if you want to swap in thin for standard-thickness grips, you'll have to also change the grip bushings and screws. The old bushings can be hard to remove, and you risk damaging them in the process. I describe how I used the Challis bushing removal tool to deal with this exact problem in this video.