Bona makes a non-toxic variety of refinisher/top coat, so that might be worth looking in to. I know they sell it at Ace Hardware, and possibly also Lowe's (not sure what's available in your area). I've never sniffed it, so really not sure if it might still have some smell to it. We also got a cheap hand rotary sander at Harbor Freight for something like $30, which we have been using to sand down the subfloor while putting in our hardwoods (alas, nothing was under our carpet except OSB!
). That might work pretty well, assuming they sell a really fine, fine grit sandpaper. I would also watch Craigslist in your area, you might be able to pick up one pretty cheap if you don't have a Harbor Freight.