The antshares testnet had been running for 8 months, and mainnet will go live probably in Sep/Oct. So ANS is not listed on exchange yet.

But one early backer created some IOU of ANS to be traded on Bitshares' built-in exchange. The most recent price is about USD $0.22 per ANS. It could be a loose price index.

Note: this early backer is not a member of TAT (The Antshares Team) and the IOU is not TAT endorsed.