Dembele has certainly performed much better than Martial did in France. Sofiane Boufal has performed better than Martial did as well. Lots of people dont want Dembele though until he signs for Liverpool and PSG, and then people complain there are no players available...
Or maybe just no one avaible for any sane amount of money. It is ridiculous to spend +30M.€ on a young striker, that has proved himself during such limited period of time. I mean who is actually worth that big amount of money? IMO Martial still wasn't worth 50/60 M - you could give 5-6 promising young players a try for that amount and spread the risk a little. But for a desperate Manchester United who swims in money, maybe he was worth it - not anywhere near worth it for us.
I mean what is someone like Lacazette (a fairly young, solid goalscorer) worth if youngsters like Dembele is around 30 M.? I would say HE is worth 30 M. not the young risky players. The hype of someone like Dembele is unreal and surely his price will end up being too much, it is too easy to assume that a young player will continue his good performances, but guess what - that is a very risky bet. We should take risky bets with young players, but not put it all on one hyped player.
Unfortunately a madness-transfer like Martial seems to be sufficient justification that young players are just incredible expensive and if you don't pay the prize, you will get no-one. I won't accept that view - if properly scouted we could take a chance with some teen players, who are younger than we used to sign, but who hadn't have their big breakthrough yet. That could be some not-hyped french players or south-americans - as long as we don't pay +30 M. for 18-year-olds who has performed in only 22 games.
If he is the world biggest Barca-fan and would prefer to play for us and turn down every other big money other places + we could exploit the small clubs inexperience with negotiating, then we could consider signing him for 15-20 M. tops. More Halilovic-signings and less Martial-signings for us please