Kayak Fishing Stuff has a great selection...and they have some boat lights designed for kayaks (since you mentioned night paddling). Around here, those lights are required if visibility is below some minimum (I don't recall the exact details since I don't go out in that kind of crud).

I don't have a flag on my Hobie yet but I've been thinking about it. Haven't encountered any stupid boaters yet and normally fish on places that limit boats to electric motors so it's hard for them to zoom past...