Maybe:
local onBuy = function(cid, item, subType, amount, ignoreCap, inBackpacks)
if (doPlayerRemoveMoney(cid, t[item].buyprice*amount) == TRUE) {
doPlayerAddItem(cid, [t]item, amount)
doPlayerSendTextMessage(cid, MESSAGE_INFO_DESCR, "You have bought " .. amount .. "x " ...