[Beretta55]

Assuming your into hack-n-slash games still I have a decent list for you (most can be found at a 20-30 dollar level.) But seriously prepare for a pretty large list, not all of them are winners but almost all of them are damn cheap.

Drakengard 1-2 (try circuit city for the second one, I got it there new for 16 bucks. The first one can be found cheap new or used almost anywhere.)
Genji: Dawn of the Samurai
Blood Will Tell
Devil Kings
Ghost Rider
Shinobi and Nightshade
Samurai Champloo: Sidetracked (be warned though, it’s made by Grasshopper, the guys who made the fantastic Killer 7. So from what I've seen it looks hack'n'slash but it may be far different from one given that a lot of their games have unconventional gameplay.)
Spartan: Total Warrior
Bujingai: The Forsaken City (I thought this game was extremely bland and plain though, and I love hack'n'slashes, you might dig it though.)
Samurai Western
Gauntlet: Seven Sorrows
Forgotten Realms: Demon Stone
Eve of Extinction
Musashi: Samurai Legend (hack'n'slash with decent RPG elements, all boils down to stabbing people in the face though.)
Nano Breaker
Chaos Legion
Crimson Sea 2
CY Girls (I personally thought it sucked.)
Maximo 1 and 2
Mark of Kri
Rise of the Kasai
Shadow of Rome (sorta. The sections with the soldier turned gladiator are pure hack and slash bloody goodness. But they are broken up by stealth sections by your buddy trying to prove a conspiracy and get you out.)

There are a few others I have not mentioned but they aren't very good at all.

Then here are some other games that aren't exactly hack'n'slash but are still heavy on action, my favorite genre: the beat'em up. Not a big list though sadly. Again these games can be found for cheap you can get Urban Reign and Beat Down for ten bucks each at a local best buy.

Urban Reign
Beat Down: Fist of Vengeance
The Warriors
God Hand (You must try this one without fail. It's a tough game like DMC3 but it is everything a 3D beat-em up should be.)
Mortal Kombat: Sholin Monks
The Red Star (not out yet, but will be coming out next week for 20 dollars.)
Final Fight: Streetwise
Rise to Honor
State of Emergency (the second SOE you might find when looking for games is more of a third person shooter then the beat-em-up the first one is.)
Oni
The Hunter the Reckoning series
Seven Samurai 20XX

ALL these games are for PS2, just to let you know.

As for RPG's eh I know plenty of RPG's that aren't final fantasy. The Star Ocean and Radiata Stories are a good pick since the battles are in real time. Rogue Galaxy and Valkyrie Profile 2 are real-time as well. So those games have a hack and slash type of play but with a deeper RPG background. As for the RPG's you listed having a tough time to find cheap, well there really is no other way to get it. The games are exceedingly rare to find and thus jacked up prices for even used copies. I'll look around and send you a PM if I find anything though.