Damn you're a big guy and I have never tried to advice to anyone with your stats.
After some research I can give you a little advice.
You need a board big board I think a 164-166 and the board needs to have wide waist around 265 or more.
Here are a few find that should work fine for you.
Lowest Price on Salomon Tempest Snowboard 166
this one looks like a great choice
Best Prices On K2 Union Snowboard 167
Lowest Price on Burton King Snowboard 167
Lowest Price on Rossignol Circuit Plus Wide Snowboard 166
Lowest Price on Ride Decade Wide Snowboard 165
Lowest Price on Nitro Target Select Wide Snowboard 165
Lowest Price on Rossignol District + Wide Snowboard 166
Or even a Rome Flag 168, personally I love rome, but I am not sure if that board might be to long for you.
I am not even going to recomend the Burton custom wide because the waist of the 167 is only 262.
I am not related with sessignol or nitro boards so I am not sure if they are good or no. Some else can help here.
As far as bindings go I always recommend the Rome 390's, but make sure that they can fit a size 15 in there, before buying (contact the company).
Boots : Burton, DC, Vans, make size 15 boots and you can probably find them cheap. I personally love Salomon boots but you have to check if they make them in size 15. The are very nice and comfortable.
When is the best time to buy Now
, everyone has great sales, they need to get rid of all the 07 gear, to bring in the new one.
I think with a board with a waist of 265 or more you might not need the elevators, but then again you might still need them.
Look around find yourself a wide board, I gave you some great links with some good choices. But check other sites for a better price.
Let me know if you need more help.
Where in Fl are you? I am in ft.lauderdale