What is the best Enduro or, street legal bike to start on?

I am 6'2 200lbs. Never ridden motorbike. Looking for the best and cheapest option for a beginner street legal dirt bike. I live on the coast and want to mostly use it to get to the beach 20 km down the hwy. Also want to use on dirt roads. Need to get my skills ready for Costa Rica in the winter where i want to be ready to ride. Thanks!