Not all that familiar with Freelancer but, if I was running a for profit business, I would feel free to experiment with pricing. If I wanted to raise my fee from $25 to $50 I think the serious reason would be, I want my business to be profitable. Sometimes when you first price something you are just kind of guessing what the correct price is. If you pick a number too low sure your customer might like it, but it may not be good long term for the business. So you have to iterate on price.