There are numerous aftermarket and factory recovery bottles available. The cheapest I've seen are plastic and mount in a crappy wire rack. They do work even if they're ugly. I ran one of the street rod stainless cylinder style bottles for years and never liked it. It was too tall and didn't work well. The bottle was always empty and there was always about 1/4" of air space in the radiator.
Back in April I switched to a Jegs aluminum tank as shown at the following link, and installed in the photo below. It fits nice and works perfect. When I open the radiator cap now the coolant a bit of coolant drips off the cap - it is completely full with no trapped air.
http://www.jegs.com/i/JEGS/555/51137/10002/-1[IMG]http://img10.imageshack.us/img10/1047/bottlewc.jpg[/IMG]
