is there where i can get extra lvl 4 key spheres or lvl 3 ones except for fighting boss battles and getting them. Im thinking its possible..i just dont know where to get them. I was able to get a bunch of lvl 2 key spheres at the zanarkand runes.

There were a few chests along the game where i found lv 4 key spheres but not many and the only one i remember is in the Omega ruins. But there arn't many and the easiest thing to do is fight certain bosses, like omega who gives you about 6-8 lv4 spheres, i think it's around there.

<font color=red face="comic sans ms">Bribe Chimera Brains on the Calm Lands to get a few Lv4 spheres. For Bribe to work effectively you need to pay enemies 15-20x their max HP (it varies from battle to battle); most people recommend paying around 1.4 million gil or around that. If it doesn't work first time, keep bribing for 1 gil at a time until they finally go away.

You should be able to get level 3 key spheres from the Zanarkand ruins. Find Defender Z's in there; it's likely you were fighting those in order to get the Lv2 spheres anyway. They drop Lv3 key spheres from time to time.