One of the first jobs I got before all my advertising came out was refinishing someone's engineered floor. It was about 100 sq. feet. I rented a Super 7r and a Clark buffer. I edged the whole thing buffed it out and spread 3 coats of acid cure. Barely broke even on that one.
Now, my minimum charge is $600, no matter how small the job.
Then, I didn't have my own equipment. I rented everything for the first year. When my advertising came out, I landed my first job measuring over 800 sq. feet. I ran out a bought a Hummel for that one and continued to rent the edger and buffer. Then, I later purchase the edger I was renting. I purchased equipment when I became really too busy and could not afford the time to the rental store or even justify the extra expense.
I poured a lot of money in advertising in the beginning. I have just recently backed off the advertising because of word of mouth.
I don't know if my little story helps you at all...but I hope so.