How old are you Oscar ? You can start racing in Senior Max in Ireland aged 15. Have you had a look at the site below ?
http://www.irishkarting.com/starting_out.php
There's also a buy/sell section on the site.
http://www.irishkarting.com/buyandsell.php
Another option is to give Noel Brennan a call for a full run down of how it all works in Ireland. I used to race against Noel back in the day... he run's his late father's [John Brennan] kart business these days/
http://www.irishkarting.com/brennan.php