Most of my laptop experience is with Dell. They do tend to have a lot of docking options and usually they can be found pretty cheap on ebay.
Though the newer laptops have a "smart" plug. These newer ones suck because no one makes a replacement so you have to get one made by dell and they tend to be more expensive as there is no competition. Though you can usually scope one on ebay for not too much.
As a for-instance. I'm now using a Dell Inspiron 8600. I get a dock and monitor stand. I go to plug it in and it doesn't work. Tells me the powersupply isn't rated high enough, which is BS, it would be fine as I'm not running the lcd panel. So then I had to go buy a bigger ac adapter.
You also can't use something like the Carnetix laptop supply to power it. This point really sucks.