Litko Aerosystems is having a free weekend shipping offer.
From their website:
We are offering free Basic Shipping today through Sunday on online orders of $100 or more.
This offer is good for both Domestic (USA) and International orders. Free Basic Shipping gets you free ground (or ocean) shipping through a carrier of our choice.
No coupon code is required, free Basic Shipping will be automatically available once you reach a subtotal of $100 or more. During checkout, you simply need to select free Basic Shipping as your shipping choice. You may also choose a specific shipping option, but you will no longer qualify for the free Basic Shipping offer.