Here is an option for you, I have a Hydroslide Ozone with Holdum bindings that I will sell for $200 shipped in CONUS. It is a six-fin board, 137 cm long, and performs well. I rode the same design at the INT Nationals this past year and did well on it. It is not the board for an S-Bend. It will get you through your 360's, rolls, and tantrums. The bindings will fit just about any adult. The board is well made and I have not broken one yet - and this is the board I use for clinics and the boat-load of people.
After a couple of years, get an advanced board after you know what works for your particular style of ridings. Keep this board in the boat for the new riders and maybe make it your slider board. email@example.com