Newly-promoted Swindon Town lead the chase for Grabban’s signature and Evans has been assured that money from the sale will be made available for team strengthening.
Grabban, 21, has scored 21 goals since joining the Millers on a free transfer from Brentford last summer.
Ironically, Evans failed in his own bid to sign Grabban three months ago when manager of Crawley Town.
“Lewis is a talented boy and I don’t want to lose my best players but everyone has a value,” said Evans. “In today’s market, he is easily worth £300,000 to £400,000 of anybody’s money. But it’s not about the money. It has to be right for the club.
“I want to make fans aware of the situation,” he added.
“And, if ever an offer is accepted, the chairman has assured me I will be given the funds.”
The Millers, who visit Aldershot Town today, still have a mathematical chance of gate-crashing the play-offs with two games to go.
However, they need maximum points and are also relying on others to slip-up. Aldershot, who are a point further behind in the table, are also still in the hunt.
Evans said: “Until it is mathematically out of the question, you have to keep pushing. If we get two more wins, let’s see where it takes us.”
Millers defender Troy Brown, who has been on loan at Aldershot since January, is inelgible for today’s game but Evans says he could still have a future in South Yorkshire.
Goalkeeper Andy Warrington, meanwhile, is hoping that good performances in the next two games will help secure his future at the club.
Out of contract this summer, the former York City and Doncaster Rovers goalkeeper was recalled for last weekend’s home win over Morecambe after a spell in the wilderness under former manager Andy Scott.
Now 35, Warrington said: “My time here was fizzling out. There is no hiding that. All I wanted was a chance.
“Hopefully, I’ve done enough to stay in,” he added. “Everyone knows how I fell and I’d like to earn a new contract.”