Obviously I'm not talking about Spurs 20 years ago, as you well know. I'm talking about them in the last few years.
Players signed that are well before their peak, who will improve and grow massively in value. Lloris (£12m), Dembele (£15m), Vertonghen (£10m), Eriksen (£11m), Alli (£5m), Dier (£4m), Alderweireld (£11.5m), Trippier (£3.5m), Wanyama (£11m), Walker (£3m), Rose (£1m).
None of those players were at big clubs that would be out of our reach. Obviously prices have inflated so we're not going to be getting anyone for £1m but that model has worked and, along with exceptional management and coaching, has transformed that club from an also ran to a team that can get 86 points in a Prem season.
Its nothing groundbreaking though. Its the same as we've done with Baines, Jagielka, Lescott, Coleman, Stones, Lukaku, Arteta, Cahill, etc who all were bought and saw their values rise exponentially whilst with us - some we sold, some we kept too long and lost the value on. And for every one you've listed above there will be 2 that haven't worked out, the same as we've had. You've got your Lamela's, Soldado's, N'Jie's, Townsend's, Yedlin's, Paulinho's, Lewis Holtby's, etc.
In Pickford, Holgate, Keane, Gueye, Lookman, DCL, we've got young players bought before their prime who's value we hope will continue to rise.