A couple of questions/suggestions--
Are you desperate to buy now? If not, you might want to wait until the summer selling season is over. You will more than likely get a better buy next fall or winter. I've watched prices drop for several years now and fall/winter seems to be the time prices start dipping after the sellers once again missed the summer selling season. Also, waiting until after hurricane season is a good idea.
Why Phase II? Phase III seems much more appealing. The pool in Phase III is less crowded, no through streets, better access to the beach by crossing the bridge into Phase I, better lake access, etc.
Given the current market conditions including the HUGE amount of inventory on the market, I wouldn't pay more than $100k to $120k for an average sized lot in Ph II or Ph III. That would put you in the range of 2000 level pricing. Prices are already headed toward 2000-2001 levels may go lower still.
In 2000, some lots in Ph I were selling for under $200k meaning Ph II and III would likely have been in the low $100's had they been selling those lots in 2000. Many of the lots originally sold in PH II in 2002 were sold at $150k to $180k.
Prices in some places have already fallen below 2000 prices. It appears WC prices are headed there too.
A recent lot sale (feb 2009) listed on the Walton Cty website in Ph IV was at $48k

--it appears to be a foreclosure and there may be something weird with the sale, but that is how it is listed on the county website. A lot in PH II sold in Feb for $225k or 12%
below the original
2003 purchase price of $261k and a lot in PH III sold for $250k. However, there are now numerous listings for under $200k-AND they are not selling. That should tell you something about future price trends.
Remember, it never hurts to put a lowball offer on the table. The worst that can happen is a NO Thanks.
Good luck.