I run my campaigns with low magic, especially at lower levels. The spellcasters that are (Bard and paladin in one game, sorceress in another) are using their spells to support the party in place of the "usual" items (Magic Weapon, Mage Armor etc.), which means less spells left to use against enemies. Less NPC spellcasters as well, and lower level.
Some spells are also banned - no flying hasted improved invisible mages around. No teleporting services at every corner.
No magic shops - maybe a big temple may donate a few potions and scrolls to a party working for them, or a mage may part with some scrolls and potions, but no magic shopping malls. Powerful magic items are generally found, not commissioned - you may be able to get a +1 sword, but you will not find a mage willing to build you a keen +2 surestriking sword. OTOH, many magic weapons will grow with the user through deeds, divine intervention and freak magical accidents.