Personally, since they offer the small 5 packs of weaned I would order one of those, then one or two 15 packs of smalls for a single snake.
I also weigh and sort my prey items when I get them. I bag them in ziplocks of 3 or 4 and then put the small ziplocks into a gallon size zip lock freezer bag. Then I put that inside a Wal-Mart or grocery bag. This helps to find just the size I need quickly while only having to open what I need, keeping the others unopened and fresh.
If you get yourself another snake or three it helps with ordering bulk to help absorb the shipping cost! wink wink!!