I didn't check it out much, but at the local sporting goods store in Seattle (Big-5) I saw a single speed with 700c rims, steel frame for about $110 I think maybe more maybe less.

If the crappy bike manufacturers of the world aren't making simple steel utilitarian bikes, they should be. I'd buy one and I already have 2 bikes.

Steel frame, steel handlebars (for safety), sealed bottom bracket, 5 speed rear derailleur and friction disc brakes. 25-30 lbs is fine. Doesn't need any aluminum except for the rims and the chainring.