If you want to go sailing, buy a fibreglass boat. If you love sanding and painting and fettling, and don't particularly want to get out on the water, buy a wooden boat.
Don't get an open dinghy unless you really are planning on keeping it ashore and launching to sail then retrieving. A much better prospect is something like I have, a small 1980's cruiser. It's only 18ft 6 and when new in 1983 was described as a "spacious family cruising yacht" a description we would laugh about now. But having the cabin to store all your gear and having a self righting boat that's unlikely to capsize anyway just seems a much better way to sail to me than an open dinghy. You will buy a boat like mine, a small 70's or 80's pocket cruiser for the same money you would spend on a good dinghy.
Don't buy a "project" boat. History has shown anyone who does either gives up, sells it at a loss, or never gets it finished. And on the rare occasion they do, it has cost twice as much as it would to get one ready to sail.