Design is way more than a bunch of generic UI elements put together on a page. This will not help you and only further cloud your understanding of what design is, and it will hurt your start-up more than any good it will do.
Trust me.
Really good designers are hard to find/likely already occupied or juggling multiple projects at a time. IMHO, design is a never ending process.
You'll hire a good designer if you get lucky at your early days but then retaining them becomes exceptionally hard. I've found that having them onboard as a co-founder seems to be the best way to work through this.
Companies like Square, Stripe value design, and it shows because they ultimately make better products that people want to use.
If you have a startup, find design talent. They are out there and itching to make the next big thing.