Monopoly Streets

Very easy to get either by normal play through of the game(s) or you can make custom rules to either deal out the properties or turn on forced auctions. There are also a few game modes that will help at this as well. The absolute best and easist way is to the bull market mode (if im correct in the name) Its forced auctions but from the start of the game, use 4 controllers and just have your main account pay $1 for them, rinse and repeat until achievement unlocks.

Edit: no need to end the game and start a new one. Trading the properties between players will get the job done. Completed this with 3 profiles and i dummy player. after properties were dealt out (no need to pay $1 as player one will win for $0 if no bid is made) simply trade them between players until the achievement pops.
Posted by BUILT TO HURT on 07 Feb 11 01:52:25 I added this comment as it does make it faster.

another way is to have two controllers plugged in and have the one who is getting the achievement have all the properties and just keep trading them back and forth till the achievement pops

Difficulty: 1/5
Time Needed: 2/5
Not a hard achievement. Either play with 2 controllers or find someone to help you online and select the Bull Market game type or have your helper select it. Then just keep bidding and winning the auctions until you reach you acquire your 75th property. This could take 4-5 games or more.