I had to re-layout my city (level 27, 200k population) and ended up bulldozing all buildings. It was just too difficult to keep moving things around. While I didn't do the "money exploit" I did obtain about $100k just by rebuilding back up to a 100k population.
I don't think it's necessarily cheating to bulldoze and rebuild to collect the building profit. It is allowed "exploit" and does take time to eventually rebuild. If you really want to sit there looping rebuilding the same building you can but that's certainly not any fun and I think a lot of work just to make some fake dough. You are welcome to do the same if you so desire.
You can still buy out the expansion items with a small amount of cash ($20k). I've always used the GTC to buy expansion items low and resell at max value since I started. You shouldn't have any problem buying expansion items at max cost. The trade center implementation has room for improvement, I don't think rebuilding to collect simoleons is the problem.
