Or: it never rains, it pours.
I went looking for a photographic store or a computer store. I trudged across streets and whole city blocks without success, then I found a whole cluster of stores in one place. Apparently, in Ho Chi Minh City, if you find the one place you're looking for, you find them all!
I had passed a city block full of bookshops, another full of art supply stores, another full of shoe shops and cobblers, another that was exclusively for bags and yet another full of office supply stores.