Hi Ganaga, welcome to coffeeforums. I think the key here is your opening words..."completely new to this business". I would say if you had spent some time working in a cafe before making a decision to move forward and start your own cafe- then there may be less urgency to have the specialty advice of a company with knowledge of the coffee business.
Not wanting to put you off (I am sure if you read through a number of posts here on this forum and others there will be ample counterbalance to teh perceived positives of opening a coffee business)- I think for sure you should perhaps try to spend some time working coffee retail before taking the plunge with your own hard earned $. I am not sure about others here, but I can say that I still work 100hrs plus every week. I am currently opening my 8th cafe, it doesnt get any easier work-load wise believe me! Also you need to be aware that if you take coffee retail seriously, and I am sure you will, the hours take a huge toll on family and personal life!
Anyway back to your question. When you look at the cost of hiring a company yes, for sure, consultants do look expensive. However they often have the experience and the know-how to ensure you steer away from problems beginners often encounter- poor location selection, inadequate training, supplier issues and most importantly developing and maintaining your brand.
IMHO I would say...yes, look more into using a consultant. Minimalising the risk of failure is really key to anyone in any business venture. Coffee is even more brutally competitive- 9/10 cafes fail in the first 2 years in the area I am...
Anyway- good luck and again, welcome