I mostly make 12"x16" darkroom prints but finding an afordable A3 size scanner to digitize them for web display is proving difficult.
I'm wondering if anyone has used a copy stand and digital camera instead? They don't need to be super high res images as I only need them for web display.
Yes I've used a copy stand and digital camera to digitize flat artwork. It can work well. Although a copy stand might be ideal, you don't necessarily need one. If you can find a board of suitable size then you can prop it up at an angle (maybe 15-20 degrees) and use a tripod. Beyond getting the sensor parallel with the artwork, it's mainly the lighting you need to think about - presumably you want even illumination without reflections? What's the finish on the prints? If they are matt you won't have as much trouble with reflections/hotspots. It's also easier to avoid reflections if you use a longer focal length lens and have the camera further away from the artwork.
Cross-polarise your lights and lens (you must use hard reflectors for this), get everything nice & parallel, a solid tripod, flat field lens etc & you'll get good results. A copy stand is useful (ideally something nice & sturdy - Linhof, IFF, De Vere etc) but not essential.
Are the prints flat or mounted? If not they might have a slight bend to them. Try using a metal surface as your support with magnets to hold down the prints. Painter's and artist's/drafting tapes work well, but you need to be a bit more careful with them.