I've come across a few online paper sellers that seem to sell the sort of thing you're looking for, one sells a
sample pack of greeting card types for $8. Might be useful if you're just trying to find a type that works best because you could print the same image on each of the samples and make a decision about what works best. They also have
glossy greeting cards. (There's also
PaperSource which I've heard good things about, but they don't seem to have glossy cards).
And last but not least I was going to show you an example from another Flickr member who was discussing making cards. The example is similar to Teewinot's and can be seen
here 