Taking a gamble as you do i recently purchased a pair of Size 8 Suede over the knee platform boots. The boots in question i obtained from an ebay shop Branded Shoes & Boots and was amazed at just how comfortable these boots are.
I wore them for virtually the whole day yesterday and must comment at just how tasteful they look as well as a lovely feeling. The suede of the boot runs over the platform which is a mere 1 inch (2.5cm) and the heel is as a sturdy tapered block 5 inches (12.5cm). The zip runs the length of the boot and matches the colour of the black suede.
I always worked on the premise that you got what you paid for and so at a price tag (post auction) GBP19.99 i am very satisfied.
On Amazon.com they have some lovely boots by Michael Antoinio which you can see here.