Suggest an ability that can be added to any item, call it "Wild", which allows the item to remain functional when in Wildshaped. Then negotiate the cost, either a flat amount (e.g. 4000gp) or a percent (e.g. 15% price boost).
IMHO, as you gain levels your items will become more and more essential--the game assumes you have them, and animal (and to a lesser extent elemental) forms just don't keep up. Without some ability to keep your items functional you will end up afraid, rightfully, to use your main class ability.
rant: This problem is an unfortunate (and unnecesary, IMO) side effect of WOTC's nerfing of the always popular (game-slowing, munchkin-loved) Polymorph spell.