I saw Isaac Florentine's Undisputed III: Redemption last night, and while it is exactly what it appears to be (a prison fighting tournament movie), it's in a class all its own. I wouldn't call it fight porn, but it is the result of letting guys who really know staged combat and choreography run the show.
The end product makes me wish that someone would reboot the Street Fighter franchise (yes, again), attach a competent screenwriter, and give Florentine and fight choreographer Larnell Stovall the reins.
These guys know how to play in multiple fight disciplines and how to not make you dizzy while watching them. Watching "action rental movies" with my dad growing up, his litmus test was whether or not it had "una buena accion" (good, solid action). You don't watch this stuff expecting Oscar-caliber performance or structure, but rather, engaging kinetics.
The Blu-ray and DVD are currently at the ridiculously exorbitant prices of $31.49 and $21.49 at Amazon, so rental is your best bet for now. With no extras at all, it seems targeted specifically at that market anyway.