I think they're earsier to make than to cut out and afix purchaced ones. I use little rectangles of tissue paper with one edge wetted with thin super glue. I just touch the edge to a lance and capilary action afixes it to the lance. Hit it w/ accelerator or simply wait a few seconds and the bond is perminate. This done dip the glued flag in a standing drop of thin superglue and saturate the tissue. This gives you a strong flag that can be then cut to final shape and folded to make appear as waving. I do this as the last prep before priming. Painting pennons is very easy. I find all of this far easier to do than cutting out photocopied or printed flags, folding them in two and gluing them together around a lance to form a 2 sided pennon. Getting the folds to line up and not be covered in white glue is difficult.
If you are set on not painting your own, here are many web sites with pennons and flags that allow you to down load. Edit copy a design to a wordprocessing file as a box graphic. Most word processing software allows you to modify the size of graphic boxes to fit any scale. Remember to print the flag design twice side by side leaving enough space between the two sides to wrap around the lance. It might be necessary to reverse the image of one of the flag sides using editing software, but this is easily done with one mouse click. (Letters will however be reversed) Copy the edited design as many times as you need and print your flags on a good quality color ink jet printer using regular paper. Finish the flags using the second method discribed above. I use downloads/wordprocessing to make flags for my 1:1200 land ironclads.