You know what, after living with four babies I know how amazing this is. Baby gates that attach to the wall are pricey brand new and don't look very charming. Via Kelly Rae Roberts.
This would probably be even cheaper than a baby gate. Here are some doors via Home Depot. The hollow cores look like they are $22 while the solid ones are $29. Just cut in half and add a 5" rounded lip to the top. Install like regular door.
These are very cute & functional - personally, I think they're safer for little fingers & toes. My office is across the hall from a non-profit urban art kids' program and they have one of these they use to corral their little Picassos. All the teachers have told me they're a lifesaver!
Sadly this would not work for everyone, although it would be a cute idea for some places. I'd never be able to use these on my stairs (3 story house) because there's just no place to open it onto. I have to use the accordion baby gates. Another issue: harder to see through.
For the vision issue you could cut out the square panels and put plexi glass in with molding around to hold it!