I don't think KM even offers hay in 5 lb. quantities? I believe the smallest is 9 lbs. If I had two piggies and was going to order from KM's hayloft, I would get the 25 lbs for $13 + shipping. It's a MUCH better deal even with the added shipping cost and it will last your two piggers quite a while (but not too long that it would go bad). Hay stored in cardboard boxes with no plastic bagging around it will keep for over 6 months easily.
I would suggest trying 1/2 bluegrass and 1/2 timothy. When I ordered from KM, my chins and pigs really liked them both, but the bluegrass especially. At the time, the timothy was very coarse and stiff so not their favorite of Kleenmama's. Now I strictly buy hay locally from a feed store and I pay only $30 for 130 pounds of excellent western timothy. One bale lasts me about 6 months. So to answer your original question, 5 lbs. of hay for $10 is not such a great deal from my viewpoint.