No geese can lay year round. They have a pretty short laying season. The price for adults varies on where you get them. They are easier to sex than other geese. The females look smaller than the males. The most reliable method is to vent sex them. I do not know how to do that.
I am not sure how long they lay. This is my first year with the Chinese.
The price depends a lot on where you purchase them. You can purchase day old goslings from Ideal Poultry for $8.06 a piece. Holderreads who is a very renowned breeder sales brown Chinese goslings for $30.00 a piece. I only purchase extremely cheap geese. I got goslings for $2.00 a piece from a livestock auction, and payed $7.00 for a mature gander.
Chinese geese are one of the smaller breeds and generally lay longer and more eggs than other breeds. Generally they will start laying in Jan or Feb and continue until early summer. I have heard that 30 to 50 eggs is normal total per goose. Things affect that - if they go broody and raise some goslings, etc. They generally lay one egg every other day. I am not aware of any goose breed that lays an egg every day.
Like someone mentioned, prices vary from inexpensive "sale" goslings to the higher priced "show" quality ones. Most hatcherys have the chinese in the spring when it is the laying season for geese. You could check swaps and local advertising sites for goslings and adults. Goslings generally will only be available in the spring.