King Leo's castle and The Black Seas Barracuda, even after re-release have not been available in the states in any retail form in almost two years. That is why the prices are high. If you can still find them in other countries, you should buy them. The last time we had a King Leo's Castle at my Brand Retail store was during the initial KK run in 2000. We last had the BB in 2003. So, hope that helps.
Why would you communicate a LEGEND or a re-release when they are limited in time and numbers to begin and marketed at a direct market mainly of fans who want a set brought back (obviously familiar with the company)? That is a waste of money. Both sets sold briskly in the US.
Dan Siskind designed 'The Blacksmith Shop' in 2002 for the MOC LEGO theme. It was very well done, even if Dan's design was slightly changed to make the set cheaper to the public. (He used some rare and odd colored bricks in his design)
The problem with having the general public design LEGO sets is easy. There is liability in it. You would have to enter into contracts with each designer. It could cost lots of money more then in-house designs. There is extra time involved, and LEGO would not be in control of the process. It wouldn't work well outside of a VERY un-often special event.
-Brett