There are two questions in this. The first is are there professionals out there who will help build your studio?. The other is are there professionals who will give you advice on what and what not to get?
Let me take the second question first – is there anyone who can advise you what equipment to buy?
One source of advice would be the equipment dealers. The trouble with their advice is that you don't know whether they really want to help you out, or just maximize their profits. High-end pro audio dealers are generally very helpful. But they only work with people at the high end of the business.
You could read audio magazines. But bear in mind that they never want to upset an advertiser (audiomasterclass.com doesn't sell advertising directly to any manufacturer, so we can say what we like). Yes, reviews can be useful, but sometimes you have to read between the lines to understand what the reviewer is really trying to say.
Probably the best recommendations though come from actual users. If you can find out what equipment was used to create a record you like, then you should strive to emulate that set up. If it worked for them, it can work for you.
Now, the other question. Studio building. Yes, there are companies who will do this. My old studio was professionally designed (but not entirely professionally constructed!). I bought it from a record producer and it was a lovely place to work. One windy night a large tree fell down just outside. I didn't hear a thing and the first I knew of it was when I stumbled into it in the dark!
The pic above shows a few ads from Sound on Sound for studio designers and builders. You can probably find similar ads in recording magazines worldwide.
One thing you would have to be sure about is a company's track record in studio building. Building a studio is not like building a house. It is a very specialized activity. And the air conditioning has to be right too.
Of course these services will cost you money, but I have met people who have tried 'short cuts' in studio building, and have deeply regretted the incredible waste of money they can involve.
Anyone have any studio building experiences to relate?