Gossamer Gear sells it's own high quality titanium Tite-Lite stakes. These Tite-Lite tent stakes are slightly heavier and 1.25 inches longer than the standards for those times when you want just a bit more stake.
For the SpinnShelter and SpinnTwinn, we recommend a minimum of 8, which gives you a stake at each of four corners, two guy lines, and two vestibule stakeouts. You may want to consider getting 12, which gives you extra stakes for fastening additional stakeouts or extras in case you leave one behind. This allows the use of all five stakeouts on the windward side of the tarp. For higher winds and added security, additional stakes would be an asset.