I would go against Marshall cabs, they're not worth the hassle of cr@ppy build quality. I've not heard of Road Kill, but another brand where you can get some pretty cheap and very well made cabs is Avatar. I'm currently running through one of their 4x12's, and they sound awesome. The Mesa Boogie Traditional cabs, like their Stiletto series, are attempts to get a more Brit feel, so if you can find one of those used, I would vote for that too, along with the Avatar.