Totally. A friend in I tried this (not in the US) using bills approximately $20 in value. We had a mediocre Epson printer and just did the approach of scan+print. We'd then handle the bills and throw them with dirt. Nothing fancy; just two kids playing around to get some extra beer money and also just to see if we could pull it off.

Out of the 10 times we tried using the fakes, we only were noticed once. It's very, very easy to do if you aren't trying to make a living at it.

I would imagine these days, it's even easier to pull off, _because_ of the high-tech protections. If you can replicate a single high-profile piece (like a hologram or something), then folks will probably just assume it's good. Most people don't know the tens of different protections, and anything flashy and difficult looking would work. They don't know the details - hell, I'd bet a bill with a holographic mark could be counterfeited using one of the holograms Microsoft uses on their products.