Defour is likely to make his Clarets debut against Liverpool on Saturday.
Dyche admits Burnley may continue to spend big this summer
However, in a window that has seen Premier League clubs spend over £800 million this summer, Dyche admits that record could be broken once again.
According to Sky Sports, he told a press conference on Thursday: "The market is that crazy we might have to do more than (the Defour fee).
"If the right player comes along who we've been targeting we might have to.
"A year ago Andre Gray was £6 million but that now seems really cheap, but when I took him there was a lot of raised eyebrows in that he'd only had one year in the Championship and would he do it again? Now it looks cheap as chips, and that's in one year."
Defour, who according to the Daily Mail once snubbed a move to Manchester United, is likely to slot straight into the Burnley starting XI for the visit of Liverpool on Saturday as the Clarets look to get their return to the Premier League up and running following a 1-0 defeat to Swansea City on the opening day.
They face a stiff test from Jurgen Klopp's men, with Clarets failing to record a league win over Liverpool since 1974.