Unless you own an A320, there is absolutely no reason to go out and buy a rating.
You should only ever pay for a type rating when there is a solid job offer attached to it, and even then it is far from ideal.
If you just go off and do your own training, you will only learn generic SOPs. The majority of the rating is company specific operations, so for an A320 operator to take you on they would still have to retrain you, which could still be at your cost. Generally this is why companies also want 500 hours on type, as then you have some proven record that makes it worth their while training you on their procedures.
Honestly, two operators can both be operating the same aircraft, and yet have surprisingly different procedures, which could lead to a lot of trouble if you've only learnt the generic stuff.
Last edited by RTN11; 23rd May 2013 at 19:41.