For me, it is most cost effective to buy at least 3 boxes at a time. When they arrive, I open all the boxes. I store approx. 200 in the house and the rest I put into a large plastic sealed tub and it is kept in our storage room in the basement.
The only other pads that I have bought are the ones from Petsmart. I don't know the brand, but they come in a big box - 100 ct. for around $30.00.
In my opinion, these pads from ebay are the next level of absorbancey from those I bought from petsmart.
I don't think you will be dissapointed at all