The Tweezerman badger brush has good reviews and is going for >$15 on Amazon. You can get an inexpensive boar at Wal-Mart for >$5. I have used the Wal-Mart brush. For soaps, normally a stiffer brush is recommended, and both of these brushes fit that bill for a great price.

As a personal touch, my wife went to one of those paint-your-own-pottery places and painted a mug in my favorite colors, etc.

Your hubby will not be disappointed with your choices, regardless.

Also, if he's as obsessed/interested as you say he is... (watch out for *AD)