I need help to develop a great clean website for my company (3 websites)

I need help to develop a great clean website for my company, we actually need it as 3 separate sites that match for 3 branches of the company.
We are a construction company, plumbing company and sell our own pre-fab houses.

I would like to find someone whom can help me sett up the site how i want it and in a way so that I can manage it myself afterwards.

I have made our previous website, but only with a free theme and it is not good enough.
We also need a shop function on the sites and translation ready..

I also could do whit help to find the right design, I know about how I want it to look and some features but I don't know what suits best.

I need to know about how long do you think it would take? What would be the cost?