My 2 gold
I think that the available buffs and levels are fine.
I think that the gold costs for crating the potion is OK.
Have you really thought about how many commin items will be needed and where they will com from?
Unless I did my math wrong, an AL200 pot needs 40 common items, a LF500 pot needs 100, an AL/LF needs 280, a DBL750 needs 150, a COA250/COD250 needs 200 and a CON200 / AL200 / SK250 requires 390.
Where will higher level players get these items? Likely by hunting in very low area levels, exactly where new players are trying to level at. If I wre a new player and could not find mobs to hunt, it would greatly reduce my interest in the game.