I think you're right that Liverpool probably did pay significantly over market value for Alisson and VVD, but to be honest I almost respect them for it. The club identified two weak areas and went out and fixed them, no half measures, no going for the 'maybe it'll work' option in the 30m range, just a proven player in both positions. I don't think Van Djik is 'the best in the league' (let's wait till he's had a full season for Liverpool, shall we?) but he has many attributes they were missing and seems to work well in a Klopp side. Alisson again can't really be judged until the end of the season, but if he replicates his form for Roma then he'll be a massive upgrade on Karius. If the club can afford it and it puts them up a level then who cares? Remember when Liverpool spent a ton of money on 'meh' players like Aspas, Alberto, Balotelli, Lambert, Lallana (ended up decent tbf) etc? That was a genuinely laughable transfer policy, these days I can't help but admire the fact that they pay what is needed for the players Klopp wants, I think really it's what most fans want.
Opposition fans laughing at the Pogba fee weren't really laughing, if that makes sense. You were far from at your best yet still able to attract one of Europe's best midfielders, in the prime of his career .. nobody was really finding it hilarious that United were bringing in a quality talent. I remember it changing from 'Pogba would never join you' to 'Ha! Yeah you got him but your club overpaid!!' as if they wouldn't be over the moon if he was playing for their team. Same story with Alexis Sanchez, it went very quickly from 'he only wants City' to 'what a money grabber, United overpaying as usual!' it's just standard bitterness from opposition fans who don't want their rival clubs to sign (on paper) top class players. If you can clearly afford it, which United can, who cares? It's not like walking in to Tesco, transfer fees are dependent on so many factors.
Basically, I'm not really arsed about transfer fees. We were linked to Zaha for 60-70m, obviously a fee that would have been laughed at, but I didn't really care and would have just liked him to be playing for Spurs. As long as it isn't destroying the clubs finances it doesn't really matter, IMO.