I think it is a decent, modest price. An art professor once gave the advice for pricing our art, take the cost of materials and then factor in the time you spent on it, he suggested using the hourly minum wage times two (which is $16) So I typically start with $20 an hour plus cost of material (I dont factor in if I got my canvas on sale). Then I adjust this buy how happy I am with how it turned out and how I think it will do in terms of what people would pay for such a thing.
I personally don't have children so I could not say for sure, but I wouldn't spend much more than what you have yours priced at for art for childrens room, yet I know that my mother would probably spend more. Its hard to say.