Do you not have medical bills that need first priority?
Take a bunch of time researching what you may need to do the recording studio you aspire to do. There is a whole lot more than just getting mics/interface. I could not even start to give points as to what you would need, without writing a book. There are many stickys at the top of the forums here, that will give a general direction. There are also many other resources for info on what you are looking into doing.
I have to say, without disrespect, that if you do no already know what it is you need to do this, then you do not already know what it takes to do what it is you propose. You will likely find that 20-30 grand, will barely get you the gear you need to even start to be near relevant in the advertising industry. This does not include the space, the treatment of the space, nor the engineer to run the gear you propose that will make you money. Don't get me wrong, I like your motivation, but I'm not sure that an inexperienced dood is going to make a living in your market.