We are in the midst of potty training my 2 year old. One of my friends came to us for advice on what potty to get. I had to say that the Baby Bjorn is by far the best potty I have seen. We purchased a store brand potty that went on the toilet set and it pinched and rubbed. We had to return it. We then purchased the Baby Bjorn potty seat for the toilet and the Baby Bjorn potty chair. They are by far worth the money and great purchases for potty training.
I have done a search through Amazon for the cheapest Baby Bjorn potty seats. They can vary by price because of quantity and style. So, here are the cheapest I have seen:
BabyBjörn Little Potty
$12.95
BabyBjörn Potty Chair
$27.95 or $27.53 for the pink one
BabyBjörn Toilet Trainer
$29.95
Holly and I both have the Baby Bjorn potties and we swear by them!