No one in their right mind would pay 150k down for a business they have to work at full-time 5 days a week that nets only 30k. That is what you call an awful investment.
A business that makes a 100k profit would sell for 200-300k. The owner will usually hold whats called a note and allow the new owner to pay him back over time or a bank can get involved as well.
I know this because this is what my brother did and I was deeply involved in the process.