The Highland side have rebuffed an approach from Fleetwood Town.
The Sky Bet League 1 club made their move after having watched McKay score against them during a 2-1 defeat in a pre-season friendly at the Tulloch Caledonian Stadium. However, Inverness were unmoved by the offer for a striker who has scored 49 goals in two seasons.
"I think everybody's got a price," said Hughes, who hopes to agree a deal with former Hibernian Lewis Horner. "Let's say Manchester United came in for Billy, you would never stand in the guy's way. I don't know if there's a bid come in or what it is, but if it's this late in the season, it would have to take something exceptional for us to let Billy McKay go."