@MoonyLupinBird,
My advice would be to double the size of the cage if you are thinking to buy 2. Twice that size for 2 birds or there may be tension and territorial issues. One bird maybe a bit easier to handle.
Furthermore, If you'll be trying to train the bird to talk, though sometimes unsuccessful, it can be a bit easier with one. Less distraction. Trading to talk (a few words) takes many months, if they talk at all.
I suggest reading up on budgies before buying one or more. Libraries are a good resource for info on how to raise and keep birds.
Are you a minor? If so what help will your parents provide you? What do they advise you? What pets have you had before? Do you have any
pets now? Is your home safe for pets? Any other young children in the
home?
Are you buying from a reputable pet store that provides any sort of health guarantee. If so for how long?
This is not a simple process and requires some education and thinking ahead. I wish you good luck.