A cheap and lazy option:

http://www.dealextreme.com/p/e10-1-2...r-dc-12v-51359

These are designed for 12v car systems, so at 6v they're not too bright -- an improvement from the original incandescent, but not by much. Definitely lights for "being seen," and they don't do much at all below 10mph. But you can buy a pack of two for $3.60, shipping included (compared to at least $28 for two Terralux TLE-1Ses). There are also a couple of options here, which I think are for 6v vintage car systems, but the info is sort of sketchy.

A useful thing to know (probably old hat to a lot of you here, but new to me) is that the 10mm screw-in base that you'll find on bulbs for a vintage Sturmey system is generally called "E10". It is also (chiefly in the UK, apparently) known as "MES" (for "Miniature Edison Screw)").
If you have a "newer" vintage Sturmey-Archer system (like the one on my '76 Raleigh Superbe), the taillight may take a wedge base instead; these are even cheaper, though they really end up at about the same brightness as the original bulbs:

http://www.dealextreme.com/p/t8-1-le...r-dc-12v-44684

There's still no good option for a cheap and easy standlight available in North America, as far as I can tell; if any enterprising folks are reading this, I think there'd be a significant market for a simple standlight unit that would fit inside a vintage bullet lamp shell and would connect easily with crimps or screws. Since that doesn't seem to exist, I guess I'll have to learn how to wire one up myself...can't be a bad thing!