We're working on bitcoin SPV wallet. After setting bloom filter, we only get merkle blocks, and transactions that match the hashes we set plus some false positives.
If a transaction is where we SEND coins, we can calculate a fee of that transaction, because we also HAVE previous transaction holding an output we spent.
But, if a transaction is where we RECEIVE coins, then we can't calculate the fee. Because, we DON'T HAVE previous transaction holding someone's output which he spent.
As far as I know, there's no way to request single transaction from peers.
How can we get previous transaction or at least it's output's value?