If your TA can offer a "really good price" on a cabin that Princess is selling for $999, they can also offer a "really good price" on a cabin selling for $1049 on the same ship/voyage.
And, no, you would not lose opportunity to be upgraded to another cabin. You could elect to book as a GTY in those other categories and also have the refundable deposit. Anyway, I was just pointing it out as some newbies do not realize about the non-refundable aspect. As long as you go in understanding the situation, it's all good.
ETA: Talk to your TA. Is this a new TA? There are some good online discount TA's in USA that beat pants off Canadian TA's who generally do not discount at all. So, you are lucky if you are getting lower price than website from a Canadian TA. Anyway, my US-based TA's would apply the same discount percent to either IF GTY (Non-Ref Dep) or IB GTY (Ref Dep). So, the upgrade cost NET would be under $42/pp or at most $42 approx per person. Just sayin'.