We love our homemade yogurt! We haven't bought yogurt in years. You can use a little bit of the previous batch to "seed" it but will have to start over after about 4-5 batches as it weakens. I just buy a small, plain unsweetened yogurt at the grocery store and use that to "seed" a new batch. Works great and is a lot more convenient than buying actual "yogurt starter".

We always condense our milk for yogurt making with powdered milk too. Works well with any kind of milk, I guess. Our yogurt is very solid, even thicker than store bought. For my 2 litre starter bucket I will add a cup of powdered milk.