I just bought a kerubi one and when i was searching I was pretty shocked to find that the average kerubi elixir was more expensive then the sun one,is there a particular reason for that?

supply & demand? how often it stocks in the shops, etc.

oh okay it's just that normal ones are reeeally expensive compared to sun ones which i find pretty good considereing i would much prefer a sun one :)

Mostly, it depends on the rarity of the item. Higher rarity means it stocks less in the shops, so it's bound to be more expensive :)

The rarity of an elixir is not always related to 'how much I would like it'. So sometimes you will be able to see some kinds of pets in some really nice colors, just because the elixir is cheap. There are colors like Glacier, Nightmare, Angelic, Reborn, and Nuclear, that typically do not have elixirs associated with them, and the potions for those colors can be pricey!