Laptop docks tend to be expensive. Just take a look at this beautiful but pricey BookArc. It seems Flickr user Kosuke Kato found a cheap and still elegant solution: just stick the laptop in a file sorter.
To be fair, you can't really tell what's holding the MacBook Pro in the above photo, but it reminds me a of a metal file sorter kind of like this one. (Alternatives: solid grey steel and metal mesh.) Most file sorters offer enough space to hold at least a thin laptop, if not a larger one, and if they're sturdy they should be able to support the weight. This seems like a really handy way to dock your laptop on your desk without breaking the bank.