Unexpectedly, I stumbled across some cheap wind-up toys at a nearby nature center. The basic timer mechanism seems like the same one that I had used before. It also winds down nice and slow but has longer metal axles and the winding stem is longer. I'll have to swing by and stock up.
I hit a couple of packs of motors with my on-line Hobby Lobby coupon. I got a pack of C6-0s to use in the micro-hybrid assuming my hot dog fuel grain doesn't work out.
I also got a couple of fluorescent light tube covers for water rocket use. One is the standard diameter and one is a smaller diameter (I forget the 'T' numbers). I have to gin up a mandrel to adapt the neck form a bottle. I was thinking to try to make a backslider, possibly with ejectable water ballast. Here, I also have to find the link to Peter Alway's backslider papers.