other than that batch , i stick to corn sugar. its cheap as long as you don't buy single batch measurements for $.75-$1.00. 5lb bag from my overpriced LHBS for $5.50 will prime alot of batches...and it doesn't turn into a rock if it gets a little humid
From a cost perspective, I can't see any benefit from priming with DME over corn sugar although some have reported a silkier carbonation with the former.
You may want to give kräusening a try just for the education.