Magic is nearly ubiquitous, but normally very low-level due to the constant "leakage" of magic into our realm via the Fairies. So while there is almost always a trickle of Magic around, Magic can not be counted on.
Most people have seen a Mage casting spells. And most towns have a resident low-level mage or cleric and at least one or two enchanted items. Often a town will have a central well inlaid with an ornate gem casting purify water. Or an elaborate gate that casts a ward for evil.
Merchants often have small or medium level magical items for somewhat reasonable prices.