No, you need to unlock to Omni* first, then you can unlock to RTK. The upside is the AG25 antenna is spendy and if you try to buy it all by itself, you've nearly paid for the Omni* unlock and you then get the AG25 for nearly free.

Once unlocked to RTK, it depends what you use to get RTK, as to what the subscription costs. I bought and installed my own base (for about $7K) and have no subscription fees and can have as many units using my signal as I want, at no extra cost.