Keep going. You need to learn how to deal with customers, and the more you do, the more you can improve. And if you continue to do a good job, you can get good testimonials, referrals, etc. You build your reputation that way. The more satisfied customers you accrue over months or years, the more buzz you create for your self or company. Word of mouth, really.
Now: Profit is based around margins. You are offering a service, so... look at how much others are paying other companies or people and/or what price/commission your customers are paying your competitors. Once you know those, along with your reputation, you can charge cheap, to beat your competitors by undercutting them. Or you can charge more, but this relies heavily on your reputation.
So, let's say you're looking for a game. The MSRP for games is $60. But the retailer sells it for $40 to entice customers... Thing is though, the retailer loses money, because each disc is a 50/50 split between the game company, and the retailer. Best to keep it at $60, and reap the money.
However, if you're making food. You want to buy cheap, so you can have a decent margin. Let's say you see a bag of steak for $4, but you're going to sell it for $6. Profit.