These are the prices for said players according to
http://www.transferleague.co.uk/tottenham-hotspur/english-football-teams/tottenham-hotspur-transfers
Victor Wanyama
£11,000,000
Kieran Trippier
£3,500,000
Michel Vorm
£3,500,000
Ben Davies
Swap
Moussa Dembele
£15,000,000
Toby Alderweireld
£11,500,000
To be fair, Dembele and Wanyama were in their final year of contract and I think Vorm was too. Toby wasn't wanted at Atletico and Trippier had a relegation release clause. Also the Davies swap was for Sigurdsson who was later sold for £45mill and prices in general have gone crazy lately.
I get the point that it's a lot of money but surely this summer is the one where we prioritise signing the right player over signing at the right price. Personally I don't think Zaha is the right player but if Pochettino does then I'll be less negative on it if it happens.