Does anyone know anything about keeping finches?

[Honeibee]

My sister left a finch at my parent's house for a week. That was two years ago. My parents already had a parakeet. They kept the cages next to each other so even though they were different kinds of birds, at least they had each other.

But the poor parakeept passed away a few days ago. So now this poor tiny finch is all alone. We went out looking for another finch this past weekend. After the sticker shock wore off, we realized there are so many different breeds of finches we didn't even know where to start! Theirs is a little brown one, with white with brown spots underneath. I have no idea what kind it is.

My questions are.....

Can you ever buy just one finch? All we saw were pairs.

Which leads me to conclude that they are usually kept in male/female pairs.

How do we know which theirs is? Boy or girl? Whichever it is, can you ever keep two of the same in a cage? We really don't want to have little baby finches all over the place.

Should we just get another parakeet to keep in the cage next to the finch? We can't really afford over $150 for one bird.

Any help or advice would be appreciated.

And say, if there is anyone else out there with one finch...let's talk.