Yes you can get the ring in Bastok, go to Sandy Consulate and be ahead of Sandy, if your Rank 3 you can purchase it with conquest points x2 for it.

The price of changing depends on the current nation's standing, the lower the standing the lower the price. You lose all CP and rank and start from 1 in the new nation, but if you ever change back you regain it all. Hence rank and CP are determined by nation.