Chick peas and tahini can be found in Western Canned Goods on Ba Trieu Street. Not sure about the wheat and flat bread, but WSG is a decent place to start your search.
I've actually seen the chick peas and tahini in several shops around town, even some of the traditional street markets.
I seem to remember noticing some flat bread in the freezer at Dan's Shop on Kim Ma, but you might want to call them first. Stock is fairly random there.
Chickpeas are available at the places listed above, as well as most grocery stores (Fivi, Citi, etc.).
I've seen tahini at Western Canned (as above), as well as Dan's and L's.
Believe the little deli/bakery at the Daewoo has some nice flatbreads.
I've also seen bulgur at Western Canned -- not sure if bulgur wheat, but worth a look (in the baking section).
