Lin, when we first moved to FL I purchased some daylilies and planted them, having used some bagged soil to amend the bed. They didn't do too well, however, a few years later, I discovered Ladybug daylilies in Geneva, FL. On their website, they have a "recipe" for amending our Florida soil aka, sand, and the daylilies I have purchased there are doing well. We go down every spring and pick up several clumps (around $9 or $10). Unfortunately I can't invest in the high priced ones, but that doesn't mean there aren't lots of others that are just as beautiful.
Ladybug Daylilies
My mother's Day gift was a trip to Ladybug for some daylilies. Here are some of my favorites.
Nile Jewel
Desiree's Desire
Intimate Interlude
Ice Planet
Sweet Patootie
Palo Duro Canyon
The website is www.ladybugdaylilies.com and they have lots of information on planting which I found useful.