The prochem course is a decent start imo, you will get loads of products thrown at you on this course they do use these courses as a bit of a sales pitch, although they do cover the basics of carpet cleaning very well.
I would recommend you get some Pureclean, this is one of the safest products available, and is ok to use on all carpet types. you can also use this product on upholstery.
I would get a spotting kit, some high ph carpet pre-spray (multipro) and some fabric and fibre rinse.
These products would be suffice to complete 99% of jobs that you are likely to face.
You dont need to spend thousands on chemicals, most of them you would never use, you can buy the problem sorters as you need them.
Machine wise if you get a Prochem machine you want a steempro powermax or Powerplus, there is loads of second hand ones about at the moment. If you want a new machine try
www.olympiccleaning.com you get free uk del, with a £500 saving on list price.
However
Mark