I have a 21' bay stealth and I take it to the first rigs out of POC and PA quite regularly. I get into the kings, cobia, snapper, sharks (got an 8+' hammerhead to the side of my boat, then cut the line) and occationally small dolphin if the water is right. If you want to go further offshore, a deeper V is needed and two engines would definately be needed. Now your talking $40K+.
I have looked at the Mako 284CC, but have heard many bad reviews about this boat, since it is now part of the BPS group of boats.
http://www.boattest.com/oem/general-info.aspx?ID=1470&lp_id=492&from_gi=yesThis boat is also listed at just under $80K