Look at Big Air Pylons out of Duncan OK. I had them build me a tower for my old Bayliner 185 BR and they were great to deal with and super affordable. I got the tower built to my beam width, with a 2 board rack, a kneeboard/wakeboard combo rack, 2 speaker cans, 2 Kicker 6.5" marine speakers, and a mirror shipped to my door for under $1500. I think just the tower alone with no extras was something like $800 shipped. Beat the heck out of the stealerships price of over $3000 for a similar setup, plus I ordered it on a Tuesday morning, and the whole package was sitting on my front step less than 24 hours later. Also most of their towers are reversible and can be mounted facing either direction. Can't say enough about these guys and their customer service. Absolutely top notch.
http://www.bigairpylons.com/