Advice! Building a cottage: Dream Or Reality?

We are newbies to the whole building process and we are definitely clueless about building in South Walton. After doing some research and seeing it was clear the price per sq. footage around this area is completely different, as it should be being how awesome it is. I knew nothing about "30a" until we stumbled across some property in Santa Rosa after saying we wanted to move to the beach (Destin), which we found out would not be a great place for us. I did not realize the treasure that I had found! I love South Walton! But to my despair, after researching, I realized our dream may not be a reality. My question is: Is it realistic to have a builder give you a "budget" on what they thought your house would run to build in the Santa Rosa area bay side? Is that even possible? I don't need a bid right now. I am in need of trying to figure out if this build is actually possible for us. I also feel like it would be hard to get any help because of how busy the builders are and the fact that I'm sure they are only focused on building larger homes or beach front homes, which is business I understand. I'm looking at a cottage built up with a drive under garage, approximately 1500 to 1820 sq. feet with a budget of about $300,000 maybe even $350,000( I have an Allison Ramsey Architects Study Plan that is 1820 sq.ft.) granite/wood or tile floors finishes-(I have high end taste & not a high end budget) but I know there are finishes that can be comparable to high end taste without the higher price tag.
So......am I out of my mind? Please someone tell me this could happen! Thank you for any piece of knowledge or advice. #shouldwestayorshouldwego