Jim Goodwin has vowed that "we will not be shafted by anybody" after confirming St Mirren have rejected offers for Jamie McGrath and Conor McCarthy.
The manager responded to a report that Wigan Athletic had offered £300,000 for midfielder McGrath and Rotherham United £100,000 for defender McCarthy.
Both Irishmen have a year left on deals that St Mirren would like to extend.
"We need to be strong in the market and I am glad to say the board are showing some strength," Goodwin said.
"In years gone by, I think sometimes we just accepted the first offer that came in."
Goodwin pointed to Scotland midfielder John McGinn, who moved to Hibernian then Aston Villa, and Kenny McLean, who went to Aberdeen before Norwich City, and suggested that they had "gone for pennies really".
The 24-year-old McGrath, capped once for Republic of Ireland, has scored 17 goals in 59 games since joining St Mirren from Dundalk. McCarthy, a year younger, has made one more appearance than his compatriot after exiting Cork City to move to the Paisley club alongside McGrath in January 2020.
"I don't think we have put ridiculous evaluations on the players, but I do keep an eye on the market and I do see what other players are going for and I do often wonder why our players are valued so much less than what some other players are," Goodwin added.
"There are certain players in Scotland at the moment who have been spoken about £2m and £3m coming in for them and they are not at Celtic or Rangers, they are at the likes of Aberdeen and Hibs and other teams.
"I am questioning why we are not getting those types of offers for a Jamie McGrath who has scored 17 goals."
Goodwin stressed St Mirren's valuation of McGrath was short of £1m and that they were "quite realistic about the situation".
However, he added: "We are in a strong position. Let's be strong and let's put it out there that we are not going to be selling players on the cheap any more. We don't need to."