Hi,
That's probably about right for ground. It's not much of a discount off air service at all.
I had an idea though. We recently shipped some media to Haw. and used this Priority Mail® Large Flat-Rate Box. It cost $12.95 per box to ship.
We can get about 20lbs of sand in on box. Means we would have to open up your sand and pour into bags, but that would save you some money.
On the type, CaribSea Special Grade is very good to go 3" high with. It's a good sand and very popular. I personally like the Tropic Eden Reef flakes better, but everyone has different taste in sand. I think the TE is just nicer looking, but both work very well.