I started building boards because I'm a cheap ass. When I first started doing it a whole kit was only about 50 bucks. One thing led to another and I ended up hooked on a hobby. There are safer, cheaper hobbies that don't piss of the neighbors, don't clutter the garage so bad and don't give you skin rashes or cancer. Coin collecting is far safer, potentially far more profitable and hardly takes up any space!
If you have the money, just buy your boards professionally made. Get a good one with decent brand recognition. Considering what goes in to a new professionally made board, they are a bargain.
There is a good argument for resale value when you decide to sell or trade-in on a new one. Often the shop where you bought your board will offer a discount on sequential purchases. There is little if any resale value in a shitty homemade special with a second rate glass job.
Realistically it will take you several years to get good results and those years would be better spent practicing and improving your surfing on a good board.
The guys who actually try to make a living at it will thank you. Guys on Swaylocks will call you a wuss.
That's OK... you'll be out surfing while they're getting itchy and dusty grinding fiberglass. Or sitting in front of their computer bragging about their awesome board building skills.