upgrades at port?

[jeast]

Are upgrades at the port readily available? Are they significantly cheaper? DH and I are going to book the Thxgiving Costa Maya cruise for 2008. We're going to book a Cat. 10 because we just can't justify $3000 more for a balcony room.

We thought maybe we could upgrade at the port if it ends up being $1000-$1500 or so. Has anyone does this? Is it commonly available? Is it cheaper? Do tell!

Thanks,
Jennifer