if you call the shark line, you get it for 199.99 plus 30 for shipping, not like the website says. plus they charge tax anyways, so its like the same thing. BUT in walmart the hard and rug cleaner comes with hard floor solution. ordering through the site does NOT. I just ordered it via the infomercial which is the same as trysharkduo dot com (says 50 for shipping but they charge 30 on phone) and i am going to call and cancel now. Its on backorder for 1, 2 it doesnt some with hard floor cleaning solution.
the 400 is just for hard floors, it doesnt come with what you need to do rugs like the 450 does, i assume the pads can be bought separately, but i am not sure.
my local walmart has it in stock, i was just playing with it in the store. They also have the solutions for 17$-something dollars, and the carpet was 25 and it came with the spray bottle for the hard spots as well as a bottle of the cleaning solution, and i think the pads too.
The KD400WM model has pads and solution for floors only. The KD450WM model has pads and solution for both floors and carpets/rugs. The pads and solutions for this particular item do not yet appear on their website as of this date. So buying separately is not yet an option! Can't even price the items yet to see how expensive the pads are.
You can also access info on it through the Shark website by clicking on the orange oval in the upper right corner that says "SonicDuo Details & Support". You will find info on the machine there as well as links to order additional cleaning pads and cleaning solutions.
This info applies to the Sonic Duo model shown on this page, which I am presuming is what you were interested in based on the model number. I haven't come across anything labeled as a "Professional" model though.
I hope this has helped :)
P.S. I was looking at the Shark website because I wanted to buy one of these but after seeing their shipping charge ($50!) I am now going to be buying it from Walmart.