Where's the cheapest you have found windmill palms? I'm looking either online or locally in St. Louis. I bought two last fall for $5.00 on sale at home depot but would like a few more.
Did you get a seedling for $5? I've either mail ordered mine, gotten them while on vacation, or once I found 2 of the blue pot specials locally. A 3 gallon healthy trachy can go for $20-$50 depending on your market, time of year, etc... They larger the more expensive. I believe I've seen $100/ft. of trunk as reasonable prices, but you'll probably have to mail order or stop at the further south nurseries, esp. the local/specialty nurseries. Once in a while you'll catch some blue pots at the big boxes, but you'll need to shop around.
These were about 2 feet tall very healthy looking but i lost one, think too much sun. Bought them for $5 late fall of last year on clearance they had like 50 of them, all different varieties of palms, bought a few needle palms too.
Try Willis Orchards! i got my Trachy there, and its great, and is amazingly green and lush! only problem is that if your on a budget, its kinda hard because they have a $59 minimum order!
Here is a link that might be useful: RE: Where to buy Trachy