The 23-year-old failed to get off the mark at Anfield last season under Kenny Dalglish and following the arrival of new manager Brendan Rodgers in the summer, the former Newcastle United forward was loaned out to West Ham United for the season.
"He has only played something like a dozen games for Newcastle and then he had to deal with a £35m transfer to a club like Liverpool," Ferguson told the club's official website.
"That's quite a big jump. I'd certainly not sign that kind of player for that kind of money. We've gambled on young players in the past, maybe a couple of million or whatever, but when you get that level you really have to do a bit more homework and see how he is in his second season maybe."
Ferguson's side come up against the Hammers tonight.