There are many prefab inserts and supports, the difficulty is in finding one that suits your preference. If shock absorption is what you want, then some decent products are made by Spenco, Sof and Bauerfeind who makes Viscoped. One must realize these take up some room in a shoe so there may need to be some adjustment there such as removing the innersole, or getting a larger size. Silipos makes a metatarsal gel pad that is comfortable but takes up room in the shoe.
I am personaly not a fan of all the pads sold in the drugstore. If they were so good we would use them.