Should I shop for a new driver? If so, any suggestions?

I shoot around 90 with and would obviously like to lower that number. I have a set of King Cobras that I've had for 13 years. My swing speed dictates that I use a stiff shaft and my current set are steal. I am longer than average with my driver, but like a lot of people I would like to add some distance and accuracy. Some of the newer large headed, titanium drivers are very enticing. Are they worth the 3 to 5 hundred $$ they cost? Any suggestions would be helpful. Thanks in advance!