If you are even thinking of starting a Part 135 certificate the first thing you need to do is get your application in, these things go in order received and in South Florida for example they are running over a year to even get started with the certification process.

Also, the down turn of the economy could be a bonus for you, there are companies going under everyday and you should be able to pick up a basic operating certificate pretty cheap. The regs kind of say you can't "buy" an airline certificate but there are ways around that. Plus, since you only want a simple single pilot operation you can be the CP and DO with your experience in 121 the FAA should have no grief with that.

If you find yourself really confused down the road there are many consulting companies out there that will help expedite the process with the knowledge and contacts they have.

Hope this helps.