The one thing of advise that I can give you is to start small and think big! You can make money breeding herps.....you can actually do quiet well at it too....but, it takes time, money and lots of patience and dissappointment to get their. Start off small and work with animals that you enjoy working with. Most times buying an animal you don't really like but think you can make tons of money breeding it doesn't really work out in the long run. You'll get bored of the animal or dread working with them and lose interested. Buy into animals that you are excited to work with AND have a good retail value and demand. Breeding leopard geckos is a rewarding experience but if you produce hundreds of them be prepared to give them away just to get rid of them (no offence to Leopard Gecko breeders out their!). If you want to get into high end morphs of balls or boas my advice to that is go big! Heterozygous and Homozygous animals sell extremely well, but, producing them reliably requires a lot of start up cash.
As you grow and people start buying from you you will grow a reputation. If you are honest and have good animals you will get a good reputation. If you aren't then you will still get a reputation but one that you wouldn't want to brag about.
Basically, you can make money breeding any herps out their. Some herps make more money than others. Don't let it bother you when people say you are just in it for the money. Even if you are who cares? If money is what motivates you and as long as you keep your animals healthy and they breed for you then who cares what your motives are. The end result was healthy animals that thrive. Whether people want to admit it or not money is what makes the world go round. You can only lose money for so long doing something before you go broke.
If you want to try and do this full time it'll take about 6-10 years to get to that point if you are good at breeding the reptiles of your choice. You will need high end herps and you will need lots of them. You will also have to be able to reliabily produce them year after year. Most of the profit for the first years will have to be reinvested in more reptiles to allow you to grow and not fall behind. On animal that is hot one year may not be the next so it helps to deversify a little bit to offest your losses in one end (good advise for those of you thinking of investing in the stock market as well.......).
For those of you who are interested (since my name has been mentioned a couple times in this post) I currently have a collection of about 300 animals (mainly ball pythons but I also have the odd blood and GTP kicking around too for shits and giggles). I could probably make it on my own just breeding reptiles.......but I still have a full time job working 8am-4pm mon-fri (yeah....so I'm money hungry......oh well!.....it pays my feeding bill..lol!).