I am not always good at sexing budgies but we just had one with the same colored cere. The mainly whitish colored cere as your budgie seems to have in the picture is a female characteristic. If the cere is not whitish as it looks in the photo please let me know since photo coloration online isn't always 100% accurate.

It looks like you have some very beautiful budgies and are getting a really nice outside setup for them. Hopefully with the breezes kept out they won't mind the cooler weather

Love to see photos of everyones flock and these are great!