U2 7" Singles...How much are these worth?

My uncle gave me some U2 singles since I'm a huge fan and I was wondering if
any Wireling could tell me how much these four 7" singles are. No I'm not
selling them, I'm just curious as to how much they would be worth today.

1) 11 O' Clock Tick Tock and Touch
2) Another Day and Twilight
3) U2 Three {which has Out Of Control, Stories For Boys, and Boy/Girl}
4) A Day Without Me and Things To Make And Do

Thanks for any information,
Mark

"Don't let the bastards grind you down"