Viberg is the first name in service boots--but those boots are $800.

White's Boots are just as good, but they're over your budget ($650). However, these boots do go on sale, I would expect that there will be a holiday sale soon.

Red Wing Iron Rangers are also a popular and well made choice. Street price for these boots are ~$325 and they're well worth it. Sometimes I see them as low as $250-ish.