Here is a sample json:
{"orderId":"1234567890.098876565434321","packageName":"com.bla.bla","productId":"blabla","purchaseTime":1393827852653,"purchaseState":0,"purchaseToken":"alot of bla bla bla"}
Sorry but there is no price in the purchase object.
but you can start a getSkuDetails()
request and you will get the price from that.