That's something SE can solve with quest rewards and NPC shops.

I actually think gathering gives way too many mats as it is. More limits should be put in place because for botany the only items worth anything are yew and walnut logs. For mining it's just iron, silver, gold and mythril. This is because too many mats are entering the economy. There's more gatherers (supply) than there is demand for our stuff (crafters).

So I think botany and mining should be capped at a max of 2 items per gather, even 1 for some items. For mining, gold, mythril and gems need to be rarer too.

The economy needs some big fixes, this would just be one of many things needed.