The Game's AI is quite predictable.
"...it will exchanege anything (and that includes everything)
for a monopoly..." You can choose to play the hardest level
for all computer controlled players. They all have the same
folly. I found that computer controlled will accecpt trade to
complete a monopoly of colors.
Keep trading and don't be afraid if you have to mortgage your
properties (this is part of the strategy). I always mortgage
the property i wish to trade. This set back the recipient a
few bucks. Allow computer controlled to have a monopoly by
trading for all the cards he have (that is not included in
his monopoly suit) and all his gold (just leave him like $10).
Computer controlled player even in the difficult level will
fall for that.
Lure the sucker into your properties. If he/she can't pay
the rent, he/she will be out of the game and all his/her
card will be yours. I have tried this strategy for like 15
times and i won 15 times.
It ain't a cheat but it sure is a sure fire strategy.