Economics & You, Making money in the SF universe

I was looking back at some old material I had and came across some rules I had put together for a campaign I was running. Basically, the PC's were mercs and when they finished a contract and were paid they would invest that money into local businesses. I had come up with some pretty basic tables to reflect on a monthly basis the gains and/or losses of each of their businesses. Over time they became immersed in the process to the point where much of the campaign centered around them gaining more territory from local gangs and investing in business, illegal activity, etc. <div><br /></div><div>My question for the forum is has anyone ever put together rules that would demonstrate the performance of one or more businesses that the PC's have invested in. I know that SF:AD has some tables based on freight hauling, passenger lines, etc but am looking more for like rules on economics. How much money do those dralasite steam baths really take in? Thoughts?</div>