I just picked up a wrt160N for 40.00 (open box mind you) and the first thing I did was load DD-WRT on it. I haven't tested how stable it is with connections, but I have it configured so that it acts like a wireless card. So i can put a cat5 cable in the back of the router and have a connection. So really other than the size of it, it's no different than having a wireless usb stick. Essentially it's acting as a wireless bridge. It has the option to act as a AP and client-bridge as well so all you need is a power cord (and cat5 for initial config or if anything goes wrong), and away you go. So all you really have to do is leave it in one location as the router will be connected to an AP and at the same time, you will be able to connect to it.
So you will just need your laptops wireless card.
If you are going to shop around for dd-wrt compatible routers, it's best to go to the dd-wrt website: http://dd-wrt.com/site/support/router-database and look up a model you are interested in. It helps if your in the store and that store has internet access on their computer display models, that way you can just look it up while your there.
Most all linksys routers can be loaded with DD-WRT however, some linksys models have less memory than others, so it's difficult to tell what the feature set is for each version of dd-wrt. ie: micro, mini, standard, huge, nokaid etc.. However I do believe all types of bridging are supported in all builds of dd-wrt.