Good coaching doesn't cost you anything, it will pay dividends and returns far beyond whatever your monthly or annual investment might be. Multi Billionaire, Paul Tudor Jones, pays Anthony Robins $1,000,000 per year to be his personal coach. He sees his million dollar annual investment in coaching as an investment in himself and credits having a personal success coach as the reason for his success. Billionaire, Ray Dalio, also invests millions in personal coaching for the same reason.
You probably don't want to invest millions into personal or business coaching, unless of course, you're a billionaire. However, good business coaching should give you a return of at least a 1 to 1 return (that's $1 back for every $1 invested), and well up to even a 100 times return on your investment. One good idea gleaned from your coach could end up netting you tens of thousands, potentially hundreds of thousands of dollars or more. One poignant suggestion from your coach could help you avoid losing that much as well.
As a rule, you should seek at least a 2X return (that's $2 for every $1 spent on coaching). If you spend $500 per month, for example, you should expect to find at least $1000 per month in return via increased profits, increased sales, decreased losses, new business opportunities, and a variety of other avenues your returns may show up.