You will get as many as the company requires for free.
For example:
You pay for an A320 FO endorsement.
The company then wants you to go onto the A330 as an FO - so they pay.
Your slot comes around for a command on the 320 - the company pays.
If they are then short on the 787 the company then pays for this as well.
If J* was to aquire A380s - the company would pay for this as well.
If you happen to dislike being on the A330 as an FO and want to go back to the A320 you will pay for this. Similarly if you are on the 787 and want to go back to the 320.
You only pay for the initial rating, as with the impulse guys who paid for their B1900 end then had the company pay for B717, A320 and A330 ratings.