Is a professional looking website design crucial for success?

I think that a professional looking website design is becoming a standard for startups. All the famous startups have a nice design. It need not have to be complex, just simple. If I see a website with not so professionally looking design I do not trust it so much. This approach is very strong in my country (Slovakia).

What is your experience? And please, could you have a look at my site - https://reltrek.com - and tell me something about your feelings? We are trying to find out, how important is to pay for professional design in this early stage.

Thank you much!