I'm wanting to use that stacking exploit where you make Fortify Restoration potions and then equip fortify alchemy apparrel, rinse and repeat. The problem is... there aren't any Fortify Restoration ingredients!

Salt pile is REALLY easy to come by, but you can't make a potion with just one ingredient in this game.

The only other two that appear in shops also don't seem to be there very often, and when merchants have them, it's usually only one or two samples.

Where's the best place to go for other fortify alchemy ingredients?

You can sometimes find the fish in shallow pools and streams, 'picked' the same as salmon, and you can get small antlers from deer corpses.

Where's the best place to find doe?

Deer are everywhere, try between Riverwood and Falkreath. The fish are in the small streams and pools, not the larger rivers, try at the edge of the swamp by Morthal.