$75,tops, assuming it's in vgc. Why so low? Well, it's a Sears-branded step-thru with a Shimano 3 speed, so if you bill it as a "English Racer", ppl will likely be disappointed or amused. For the most part, though, it's not got the things that ol' 3-speed enthusiasts lust after; top dollar goes to diamond-framed bikes with sturmey archer gears and classic Brit names (Raleigh, Rudge, Chater-Lea, BSA, Humber, etc). Extra dollars go to bikes with incredibly awesome sprockets, like the hand on earlier Rudge Sports, or the Raleigh bird sprocket, and pimp stuff like dynamo hubs.
I'm not trying to snob on your bike; I kinda like it, especially the brake levers. I'm just recommending that you take what you got into it, and double that, for a fair price. Remember, if you go for top-dollar on craigslist, you'll end up losing money once you factor in all the time you have to spend dealing with craigslist scammers, tool-bags, and d-canoes.