Considering what some of the rangers are going for, I'd say that is a fair price. The pricing on the green and white ranger keep fluctuating, so it's a little tricky.
My main problem is that you are selling them as a lot. I think that you will have a better chance at selling these figures if you split them up. Nine out of the ten collectors are already going to have some of, if not most of the rangers already. I also understand the risk of splitting them up, so that's ultimately the decision you have to live with.
This is why I don't buy my figures with the intention(or smallest possibility) of selling in the future. It's just not worth it and would totally ruin collecting for me.