A while back I started a public gym in Amsterdam to take advantage of lower level managers without a lot of money. Right now it is set up to a 90 fighter cap, with two elite CT coaches for $100 a month. On Thursday it will receive around $4k, and you'll probably have to replace equipment right after you buy it. A gym like this in Amsterdam seems to support 80 to 100 fighters depending on the month, and therefore brings in a profit of around $4k every 2 weeks if you immediately replace equipment. If you want to make $6k-8k in 2 weeks, simply let equipment stay at Excellent for about 4-5 days. I've made around $90k total in the time the gym has been open.
http://www.mmatycoon.com/gympublic.php?gmid=1432
Let me know if you have any questions.
-Brad