Sorry for the rant but Fonts are the most overpriced thing on the web. $775 for a collection 15 fonts is what one of those fonts costs. Give me a break.
You're underestimating the amount of work that is put into creating a complete font family -- each glyph must be drawn, tweaked for visual balance, kerned properly, etc. Bold weights and italics are sometimes created algorithmically from the base typeface, but still require further editing to look good on the page. It's the attention to detail that matters.