Hello Nacho
Well there are official whale tokens and whale tokens, the official tokens are not tradeable, you can only use them to summon shares(votes) for your blog, the other whale tokens are tradeable and thus have a value in relation to bitshares. We have so many of them, so I can't give you an exact value!

Can the WLS be changed?

Yes it can be changed on the rudex exchange, it's current value is 1.1 bitshares.
1 bitshares is 0.04$