check out
www.thegreetingplace.com
we have had this quote card company for 11 years and it does really well.
The appeal is pairing a quote with a corresponding or contrary type image.
note...women buy almost everything and influence the men when they buy...just sayin
humor quotes sell more than insight or inspirational
( more gift appeal in addition to self purchase )
and , as said ,design is everything
pick a niche and market to that, it matters more what they think than what you think
good luck