The best way to build any product is, instead of going for freelance workers who do part time.

Try to find an intern or fresher and give them a chance to learn and guide them properly.

This way you can able to get the best product and will understand to maintain a future start-up. Belive me it takes less time and less money and you'll be having one loyal employee, who got an opportunity to learn.

Sometimes it might take a little more time, but the total time wasted comes negligible. So the best thing will be stop looking for good freelancer and start searching for a fresher or one who is looking for a job. If you don't know how to hire then provide them with the resources to learn and then test after a month.

Trust us, You'll surely will get an awesome resource.