I'm suggesting the club know how much they can spend and won't fritter it away willy-nilly only to find they can't afford what they really want. What's more, while the budget has limits, there is some flexibility.
https://www.donbalon.com/futbol/premier-league/wilmar-barrios-quiere-ir-a-la-premier-el-club-con-el-que-habla
Suggestion that the fee would be a little over 15 million. This article is also quite complimentary about the club, Potter and the city. Which is nice :)