I did my backyard garden for like $60 - just a sod cutter rental and some native seed mix. This is going to be.......a lot more. I think if this were a big suburban lot - like if I were doing anything larger than this 1000 square feet - I'd do a designed seed planting ala James Hitchmough's technique.
For this space I'm happy to pack in plants from 4" pots, in large part so I'll have solid erosion control probably 2 years earlier than from seed, and it does let me control where the plants start out, at least.
I've gone back and forth with the pros and cons of seeds versus potted a lot just in general, and I have done and seen results of both (although I only have two years of experience so far).