Embroitique is my very favourite for fonts. Jolsons has fonts for $1 at the moment.
Also Applique Corner. You usually get several sizes with the sets. And they stitch out great. She does run sales often & has a Fri. Font sale for 1 day on Facebook at 99 cents for the set! Oh. Her site is 40% right now.
Apex. Someone help me with the link. Kay
This site has some monograms up to 8" and one of them sets up as big as 7x11.