Reeds can block the view when they flourish, so consider where you will be when enjoying your pond so you will see more than reeds. Another good resource for inexpensive pond plants are garden shows. Independent plant sellers often have very good deals on garden plants that they probably collected in the wild, too. Most pond plants will have to be in pots. Be careful about the pots you select.
Color is important.
You don't want to the pot to show in the water, so black or dark green is the best. Of course, size of pots depends on the depth you plant to place it. To prepare the pot, place gravel or pebbles at the bottom, a layer of soil in the middle where the plant will be rooted, and a layer of gravel or pebbles on the top to keep the soil in place as much as possible. This can be heavy if you try to use big pots. I find the one gallon variety you get when you buy plants works well, and it's a good way to recycle these pots.