It's cheap because it is the PAL/Int. version, and the requirements are quite low. If 200k is "a lot," then that means that Hillary and Obama should be able to pay someone to Zanmato their competition. Clearly has not happened, so I will pretend that your PAL Zanmato requirements do not exist. In theory, Zanmato is not cheap and is a feature of a game.

The obligatory "Tavrobel has to complain about FFX PAL/Int." being out of the way, you should invest some of your time in those Celestial Weapons. Since they deal damage based on HP (and therefore bypass Piercing, which doesn't work at all post-game anyways), it is your best option. The easiest, in my opinion, to obtain are Yuna's, Auron's, and Rikku's weapons. Lots of people complain about "omg blizbal sux," so until I have your personality's evidence to the contrary, I will forgo that option (like I could care less whether or not you play Blitzball). Tidus's and Lulu's weapons are taxing, but not as difficult as people make them out to be. Kimahri's is actually hard to get.

Also, they come with a free Break Damage Limit, which is found on weapons. Break Hit Point Limit is more or less unnecessary on armors; you can still be hit for 99999 damage with 9999 HP. No restrictions on monsters, people.

Fortunately for you, your Luck is at 255. So, don't worry about attack accuracy. Actually, you shouldn't need to worry about Evasion, either. I surely hope your invested those unused spheres in something useful, instead of doing something stupid and max out your MP. Glorious manasteal, d00dz.

Fight them one at a time for as long as you can. After all, gang kills are better than solo or team v. team.