I collected apple pollen this year, which is now available in the store here. This is pollen from select varieties that I use in breeding or consider interesting enough to use. The quantities are small as it is rather time consuming and many are in limited quantity, especially since I'm also pollinating a lot of blossoms this year in that hopes that I will have apple seeds to sell in the fall that are specific hybrids between carefully chosen parents. Fingers crossed on that, but for now we have pollen. If used carefully, this small amount of pollen can go a long way. Very little needs to be applied to the female parts to achieve pollination. You can read about the varieties on the store page.
I have stored pollen for a year and used it the following spring successfully, but at other times it has not seemed to work as well. But that is in a room with very large temperature swings and extremely hot in the summer. If you were to freeze the dried pollen I think it would probably keep well enough until the following spring. The pollen must be absolutely dry for any kind of storage and a desiccant of some kind would probably help with that. Some use rice, or those little desiccant capsules that come in jars of vitamins. Just remember that whatever you use, your small amount of precious pollen will probably stick to it.
Here is a short video on how I pollinate apple blossoms for breeding now. Good luck to anyone trying to do cross pollinations this year!