Jas, I have to agree with greenlight in a retroreflective solution will probably be your best bet. In the traffic management field, which I am in, we rely on type II strong yellow green retro reflective garments, usually vests, in the day time and type III at night. The only difference being the amount of reflective material. They are also availible in t-shirts for your comfort. You must have noticed some traffic workers wearing them and they are bright as heck when hit by headlights. There are lots of places to purchase online, this being one of many:
http://www.discountsafetygear.com/ansi-t-shirts.html
I don't know where you live, but you almost certainly have a local source availible. If you can't find something in the yellow pages under traffic or barricades, stop and ask a flagger next time you see one. I would suggest you get an ANSI approved product.
If you wanted an additional lumination source, battery powered, there are all sorts of blinky pendants and stuff, a few that come to mind are nite-ize products and sylvania dot it lite sticks