The Fonts.com™ store from Mono-type Imaging offers more than 150,000 font products for you to preview, purchase and download. You can also learn about new typeface releases and discover typographic tips and techniques.
Based in Woburn, Mass. with regional offices in the U.K., Germany (Linotype), Mt. Prospect, Ill., Redwood City, Calif., Boulder, Colo., Japan and China, Mono-type Imaging is a global provider of text imaging solutions for manufacturers and developers of consumer electronics devices. Some of they're besting selling fonts include: Futura, Neue Helvetica, Frutiger, Interstate etc... Here is a link to more popular fonts, and foundries.
Most of their fonts are at more of an affordable price than there competitors for example Fonts.com has a particular font that I like named Lomo. You can buy either the full package of these fonts for $1,661.00 or just specific fonts from the Lomo collection for $54.00 each. There biggest competitor which just about everyone has mentioned in the blogs is Fontshop.com
They offer the same Lomo font but they don't offer it in single fonts, they sell it as a whole with 37 fonts for $1,499.00.