You'll quickly kill any money saved by buying at the dock with the expense of driving around. Of course there's value in the experience of meeting locals and dealing first hand with the lobstermen/ coops, plus it's a beautiful time to drive the peninsulas, so take your pick.

Th the point that $7.99/lb seems expensive, it's not just the lobster. Not even 10 years ago I can remember retail prices starting at $3.25/ lb, cheaper even than steamers! But it's 10 years later, the world has changed and nothing remains the same. Just enjoy it while you're here and don't sweat the price, I guarantee it's a lot more expensive virtually everywhere else in the country.