Where to get narrow bars

38 is not particularly narrow, plenty available in that size. Most older bikes come with 38 as standard. If you do not mind something old, headover to any place that has a stash of older bike bits. Jumble, bike co-op workshop etc... You will definitely find some.

True. Sakae road champions are about 39 centre-to-centre at the ends and narrower at the hoods, and they're everywhere.