Josh P said:

Usually A local golfsmith will have extra headcovers for $5 a piece.

I'd like to do business with YOUR Golfsmith. Around MIami, they want around $30 for a driver cover. I got one via ebay for slightly less.

If no drill works for you there is a tool that is fairly expensive but it causes you to load properly and stop swaying the website for the training aid is http://pivotpro.net/