Donaldson, 27, scored 29 goals at Crewe last year and was crowned League Two player of the year.
Manager Paul Dickov told the club website: "I am not stupid and realise that goal scorers of their calibre are going to attract a lot of interest."
Dickov has lost a number of strikers from last season with only Warren Feeney, Reuben Reid and the club's new non-league signing Matt Smith currently in the squad.
"I have spoken to both, but there are a lot of clubs in for them," he added.
"If it is purely down to money, then they are not my type of player.
"I want footballers who will buy into what we are trying to achieve here."
Source: BBC Sport
Source: BBC Sport