Yeah, seriously, you're around halfway through the first disc, perhaps less.
Anywho, rocket launchers for bosses is pretty cheap (even though I did it a couple times >_>). This guy's actually pretty easy, so don't waste your money on him. As long as you have a few grenades and your trusty shotgun he's pretty simple. For the first form just throw a couple incedinary or hand grenades or shoot him in the spine with the shotgun. When he gets to close just run by and dodge (L+R when directed) all the way to the other side and repeat until his second form.
There's ammo and health and grenades everywhere, too, so pick some up if you can. On his second form, I just stood in the same spots as before (either end of the room by the door or ladder) and waited for him to come closer and then nailed him with the shotgun or another grenade, and then ran to the other side. On one side of the room there's a barrel you can shoot to to damage him. I never go on to the second level, I tried once and died pretty quickly.
Remember to collect all teh goodies on both floors before you leave, you can't go back in!
Oh, and his name's Bitores Mendez, the village chief!