How important would be a buyer persona for a business?

Buyer personas  allow you to better  understand  the needs  and wants of your  customers .This allows to do a more  efficient job of appealing to those specific desires . 

Buyer personas are very important in designing products or offers. In customer research we use personas to fine tune a segmentation because the demographic and other related data are not sufficient today to have a feel about users or customers.

There is a model that goes further than capturing cold data: its the persona empathy mapping. It focuses on finding out what user is thinking, feeling, doing, seing while engaged with a product. I agree this method is more useful on a UX design task but nonetheless the data collected can improve a product features and can provide new insights on the target user. 

Buyer personas are essentially a representative of the type of buyer you have identified as having a specific interest in your organisation or product -David Meerman Scott

Buyer personas provide tremendous structure and insight for your company. A detailed buyer persona will help you determine where to focus your time, guide product development, and allow for alignment across the organization. As a result, you will be able to attract the most valuable visitors, leads, and customers to your business.

It is one of the very important aspect of selling.

Knowing the persona of the buyer you are wishing to sell your product will make selling process much easier.

Buyer personality is the important aspect in marketing strategy. A successful company research closely to understand different personality traits of potential buyers before finally launching the product in market

It is very important in order to obtain the target consumers. Once it's validated, a functional product can be produced that will be a hit in the market given that proper study was done.

Buyer is always important for organization in controlling the cost and expenditure by convincing the supplier to agree for attractive prices which help the organization to achieve targeted bottom line (net profit) of the organization.

That is a difficult question, without knowing the business, it should be skill you can leverage as you are also a customer and buying in you daily life. 

What if you spent all your company's resources developing a product which "you" feel would be a game changer only to find out no one cares and you have effectively sunk the whole ship (your business) Buyer Persona gives you valuable insight into where you need to focus your resources and what you can expect from the people in terms of reaction to your product, how the people feel, how they think, what they want, what they actually need and all that data is invaluable, its the reason why companies like Google give out free services like Gmail and YouTube so that they can better understand their users and in effect create products that are targeted towards the audience. So yes buyer persona is an important part of the whole development process.

I a buyer or procurement person is very important for employers.  A sales company wants to sell the best products at the lowest and most affordable prices.  Moreover, they want to sell what people need or want to buy.  If the company buyer isn't competent the company will suffer financially.  The buyer won't hold his job for too long if he cannot negotiate costs, quality and need from vendors or manufacturers