I found these skates used on craigslist for $25. They were a size 10 and I wear a size 11.5 so I couldn't use the boots. I'll try to sell them back on craigslist for what I paid. It's cheaper to buy used skates rather than buy all the parts new online. You need the plates, 8 wheels and 16 bearings. It gets pretty expensive. I will probably buy some 72 mm Sims Snakes wheels later to make them even more awesome.
Remove the insole and unscrew the base plates of each skate. You might want to do one at a time so you can use the old skate as a reference when drilling the holes in you Vans.