The "cost" of these animals needs to include mortality rate (buy two fish and have one die doubles the "cost" of the remaining one) as well as husbandry needs, chillers, etc. - weedies typically don't thrive on just frozen mysids, if they go off feed, you'll need live mysids to get them jump started again.
Three years ago leafies were $2000 USD FOB Australia and weedies were running around $600. Leafies went WAY up this year but I did see some weedies for sale by a dealer in Japan for around $600 USD.
Here is an excerpt from my "Advanced Marine Aquarium Techniques" book:
Weedy seadragon (Common seadragon)
Phyllopteryx taeniolatus
Maximum size: 45 cm
Habitat: kelp beds, open sand areas
Range: South Australia
Only a few captive raised animals have been available. This species requires a dedicated, chilled aquarium and a consistent supply of live mysid shrimp (Although many specimens can eventually be trained to feed on frozen mysids. They are prone to an Uronema-like protozoan disease as well as bacterial infections. Combine this with a dealer cost of over $600, and you have a fish that really only belongs in public aquariums. The even more fantastic looking leafy seadragon is four times more expensive.
Jay Hemdal