Exactly. 200-250G Every week is a significant time sink on top of all of the materials for potions, flasks and other consumables you already need to farm for classic raids.
Resto shaman for raiding is definitely viable. Probably the best raid healer in the game. One option is just to spec elemental/resto (which is the PvP spec anyway) and collect heal gear with MP5 -- then just heal as elemental. All you'd really be missing is mana tide and 10% healing from purification. Something like
this? Then you'd also be able to farm dungeons with a tank and 4x elemental.