Well, I get a great deal on my wool b/c I'm dear friends with the momma who dyes & combs it. But a good price is probably anywhere from $4-$6 an ounce depending on what kind.
You're probably best looking for a small local shop with local fibers as opposed to online. When I was just getting started at felting, my local yarn shop carried "ends bags" from the woman I now get all my wool from. It was all the leftover bits & pieces from spinning and dying. A big bag of great variety of color & fibers ran me about $35.
For wool felt, your local Jo Anns might carry some wool blend felt that's not too expensive. Mine has some 70/30 and 80/20. 100% is a special order. I like to get mine from Wiers
. Sometimes they have cheap scrap bags that give you a good selection of colors for little projects. Good luck!