How to make Greek style yogurt?
Try this: Get a good plain whole fat (or low fat, if you prefer) yogurt. Have on hand a fine-mesh strainer and line it with a coffee filter or filters. Drain the yogurt for several hours. It will be thicker and not dissimilar from Greek-style yogurt. I use this method for Indian desserts etc.
P.S. I believe you can buy yogurt strainers at cookery shops.