'If you're talking £15m for Zaha, Thomas has got to be £25m,' Paul Ince told the BBC, potentially risking the wrath of Ferguson who once called him 'a big-time Charlie'.
'If you compare the two, Thomas should cost more.
'Zaha is a fantastic player, don't get me wrong. Zaha's a stronger runner and does a lot of tricks, whereas Thomas is more direct, he makes things happen and he scores goals.
'You've got a kid playing in the Championship who has scored 18 goals. When you look at the leading scorers, they're all strikers, and he's there among them.
'Potentially, I think he can reach that value. If Palace want £15m for Zaha who has scored six goals, it makes you wonder what price he's going to be.'
Ince was last month named the Football League's Young Player of the Year and has scored 18 goals in the Championship while Zaha, scorer of six, made his England debut against Sweden in November.
'You're not going to get it because he's not proven in the Premier League, but if United are paying £15m for Zaha, on the stats you'd have to say Thomas is worth a lot more than that. That's my opinion.'