I actually bought an imported NeoGeo Pocket B&W on release, together with KOF R-1. Loved the system to death, soon after I got NeoGeo Cup 98 and Sam Sho.
Kept up buying games for it until I picked up SNK vs Capcom and found out it wouldn't run on a B&W, so I had to upgrade my system. By then the slim model of the NGPColor was already out and I imported a carbon black one.
I've been building up the collection since the first day. The best time was when I visited Japan in 2001 and man y shops were clearing NGP stocks... I recall buying a handful of new games in an electronics shop in Nagoya (including great titles such as Rockman, Magical Drop and NeoTurf Masters ) for 1000Yen a piece. It's too bad I didn't pick up the rarer titles then... but at that time I was looking for fun titles, not collectibles.
Now I think I'm missing 14 titles to complete the Jap NGPC set. Most are pretty common, but I think around 4 of them will be hard/expensive to get a hold of: Cotton, Nigeronpa, KoiKoi Majong & Mesaze Kanji Ou. Not in a hurry though, I've enjoyed building this collection since 98 and, besides Cotton, all the titles I really enjoy playing are already home
MOTM is still my favorite portable fighter ever.