Depends on how you're selling them. On E-bay, it seems most U2 posters (at least the last time I was looking) go pretty cheap - like around 5 bucks perhaps.
In contrast, there was this guy who came to my school, had tons of awesome vintage posters from a huge variety of things, and was selling them (including a huge selection of u2 one's) for anything between 10- 25 dollars. (except for some really rare or high demand stuff).
He had both the one's I think you're talking of, and I think they were going for about 10$ in practically mint condition? I think? I'm old and senile you know.