I bought a cheap router for $20 shipped (2 actually, one for my parents’ house). It supports DD-WRT and I did load it on. It has dual band support and AC support. I configured it to be an access point. I do want better throughput since I find myself moving photos from the ultrabook to the primary storage.
The router is a Trendnet TEW-811DRU. It runs very hot. I’m underclocking it by 20% and it still runs hot. I’ve taken the thing apart and plan on replacing the 2 heatsinks with larger ones and will use thermal paste. Right now the transmission rate is miserable. Worse than first generation WiFi. I suspect heat is the problem.
If I can get the thing running stable, I want to also mod it further with external antennas replacing the tiny little internal ones it has now.

I need to find replacements for both heatsinks. The big one is 1 1/2 inches by 1 1/2 inches. The small one is 1 3/16 inches by 3/4 inch. There are antenna kits on Amazon from between 7 to 13 dollars.
Update 2015.08.12
I put in replacement heatsinks from some old video cards. Added thermal paste. And only could get them mounted with twisty ties.

It ran nicely with the cover off. Connectivity was much more stable.
The replacement pigtails and antennas came. I drilled 2 1/4″ holes and got the antennas in place. It ran OK in initial testing.
A few days of use turned up some substantial problems. With the cover on, it runs WAY too hot. The heatsink might be extracting heat from the chip but it isn’t getting dissipated. It is just getting trapped inside the case. Temperatures are in the 70s. Celsius. Open the case gets the temperature to a more reasonable level.
But the connectivity, while mostly stable, drops down every so often. Not good for streaming TV. The application complains about low bandwidth and stops playback. Speeds are quite good and I am getting good 5GHz connectivity and range. But stability is either a heat issue or firmware issue.
I want to try getting more ventilation for the case and maybe a USB powered fan.