Shopping in Medjugorje is almost entirely religious: rosaries, statues of the Virgin, prayer books, medals, holy water bottles, and crucifixes in every conceivable size. The stalls and shops line the approach roads to St. James' and the foot of Apparition Hill, and most of them sell roughly the same goods at roughly the same prices.
A few things are worth looking for. Olive-wood rosaries from Bethlehem and the Holy Land are a step up in quality from the mass-produced versions; some shops carry hand-carved pieces with origin labels. Local Herzegovinan wines (Zilavka, Blatina) and bottles of medovaca (honey brandy) are sold in the larger shops and make decent gifts. Bargaining is uncommon -- prices are written and stuck to.