Do we ever find out what happened to Chrollo? During the "Greed Island" arc, we learn of a nen user who can remove other's nen. When he got the Bomber's nen removed, the creature he summoned to remove the nen had to stick to him until he touched the Bomber and say the "magic words."

Kurapika's chain needle is more powerful than the Bomber's nen, yet when Chrollo got exorcised and he appears to be unscathed. There should have been some form of price Chrollo paid to get Kurapika's insane ability removed.

Do we ever find out what happened here?
Chrollo successfully had his chain removed by the Greed Island Exorcist. 

He doesn't need to pay a price except whatever he paid to hire the exorcist to help him. Gon only lost his Nen because he violated a Contract, and even then it isn't confirmed that he is completely nen free. 

Chrollo can still wield his book, and he used so very efficiently when fighting with Hisoka.