I see a few guys posting here getting keen on the racing gig and asking for advice from racers regarding gear and bike etc .... which is all good n all but perhaps a little advice about the potential economic effects is worth a mention as well so we can steer these guys into racing without them becoming financially destitute within the first few years.
As the title goes ' The Vacuum Principle of Economics' is quite relevant to motorsport.
It basicaly revolves around the act of creating a gigantic money void by spending all of ones earnings, borrowing more and more and then being sucked into the said void until the spectre of financial ruin forces a dramatic U turn.
The motorsport after life is then frequently spent scrambling like mad to fill the void before it crushes you.

That said, the advice given on the posts seems good. Be clever and start on small cheapish bikes and use what money you have left to buy the best safety gear you can afford. Generally the first crashes are low sides and running off the track etc so the mid priced gear is fine to handle that and you won't get bummed when you rash the expensive leathers.

But, whatever way you look at it, motorsport is expensive and addictive.