Martinez would cost 38m (30m buyout clause + tax), which would be about the same price as luiz (his selling price is 40m i think). And he doesnt have any experience on top level, so quite a risk.Definitely have to buy someone, but why does it have to be that they are 40m+ price tags to be considered "world class" or "barca worthy" defenders? Scout some people, find a consistent and reliable player that would fit. Just because someone plays at a lower table club doesn't mean they are shit or unworthy. If we end up having to splash the cash, Inigo Martinez or Jan Vertonghen are better options than Luiz (cheaper and more reliable).
Don't know about vertonghen, levy is such a pain in the ass, so he certainly wouldnt be cheap either. Also, why do you think vertonghen would be a better fit than luiz, which qualities does he have that luiz hasnt?