For price and sound quality on amps, I would vote for Arc Audio (KS series), JL (HD), or Alpine (PDX). Tower speakers I would invest some $$$ in Exile or WetSounds. Interior speakers I did Polk Momo's and they (Polk) seem to be the norm in many boats unless you go wet sounds here too.
All are personal preference and really how much you want to spend... both now and down the line to upgrade. I did the stereo head unit and interiors first, now starting to collect amps and sub(s). Further down the road will be tower speakers (I wish I had the cash last month when Earmark had their deals for wetsounds pro-80 and syn amps).
David with Earmark is always willing to chime in and give you his .02 cents. You may also want to cruise through David's past replies and see if anything is relevant so he doesnt have to keep repeating himself. Talk to a local dealer and hear a few speakers / set-ups, then post findings.
Don't forget batteries, perko switch, on-board charger, wires, and... ahh nevermind. You will shortly discover building a system is like remodeling a house, plan to spend at least 20% more than you budgeted and THEN tack on an addional 10%.