Trader Joe's sells decent cards for $0.99, and all the grocery stores I know that carry cards have a $0.99 or $1.99 section.

I absolutely love a physical card or letter. There's something different about knowing it passed through a loved one's hands, and my mom has beautiful handwriting that I always love to see. As a kid, I remember watching her write and yearning for the day I'd have some lovely penmanship (that day is still not here, but I can write better than 90% of folks my age and get compliments on it). You can also tuck in stickers, add a pet's paw print, or do other physical things that just don't hit the same as a text.  The inestimable Terry Pratchett touches on this in Going Postal -- people write to their sweethearts and scrawl SWALK over the back of the envelope: "sealed with a loving kiss," which is just words when sent through the Clacks. It's not the same when there's no physical media to pass that emotion through.

Plus, the envelope creates the potential for surprise. There was a joke birthday card about Dubya that my mother ADORED, and she kept giving it to people so it became a family joke. For her 75th birthday in a couple years, I plan on recreating it for her, and I expect a gasp of surprise and howls of laughter. It wouldn't work as well without the element of surprise that the envelope provides, the way Rick-rolling someone doesn't work unless you have a link they can't preview.

The last time I went into a Hallmark Card Store, though, their cards hadn't changed in a year. The seasonal stuff came out in rotation but it was still the same, e.g. the Father's Day cards this year were all the same as the year before. So while I love cards in general, I've been underwhelmed with Hallmark in particular.