You should read this article first:
General Guide to Low-Light Planted Tanks - particularly the "PLANTS" section. It will tell you what kinds of plants would be good for you. Prices for plants can range from $1 to even $20-30, depending on the size of the plant and the type of the plant. But I guess the average cost for a low-light plant is anywhere between $2-5.
Good low-light and undemanding plants are Anubias, Java Moss, Java Fern, Water Sprite, and Hornwort for example. They don't really require any special care. Anubias, Java Fern, and Java Moss are attached to aquarium decor or driftwood, and they grow their roots around the decor/driftwood. So they don't even require gravel. Hornwort can be left floating or can be planted in gravel - but this is only to weigh it down as it doesn't really grow roots either. And Water Sprite should be planted in gravel. It's a relatively undemanding plant so it should do fine even in plain gravel (as opposed to nutrient-rich gravel).
P.S. Angelfish like tall plants such as Swords and Vallisnerias, but these 2 plants are a bit more demanding than the above plants I mentioned (they should have a nutrient-rich substrate and better lighting in order to do well). As for Cherry Barbs, BN plecos, Kuhli Loaches, etc ... they should be happy with any live plants. Cherry Barbs like densely planted spots to hide in. I'd guess so do all other fish.
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Though I added a "P.S." to my post - read it! 
