Unfortunately, the cost is something that makes it out of reach for many people. And it's not just the cost of freezing - when he finds someone he'll want to have kids with, there'll be the issue of fertilizing and implanting the egg.
And were I the cisgender female partner of a trans guy, I think I would want to raise the question of which of us gets a bio offspring. I.e. whose eggs do we use, his or mine?