I do a lot of commission work myself, and even though sometimes I feel bad throwing out the high end figures, I refuse to not make something off of them because the time I use to make the costumes could be used for something else, like making my own costumes or resting after my real job.
Like recently I finished a Madam Red commission to be exactly like the one I made for myself years ago (which not to sound arrogant, but it's an award winning costume, so it's a good representation of the character). The customer asked me also to purchase the wig and boots to go with it so that it could all be sent together. With time, shipping, and materials cost, it came out to be nearly $600. I've made a decent profit on it and allowed them to make payments since that is a very high price to pay, but to get what I made (the whole costume including the hat and a nice little drawstring purse, the historically accurate corset, brooch, boots, and wig), I feel that it was a decent price.
I've had some customers agree while I've had others go "Well I can get it cheaper from [insert website name here]" and they never contact me back. It's always hard to decide what is going to be a price that will help you make a profit without turning away a customer. But I guess I must be doing something right since I've had several repeat customers over the last few years.
In the end, a lot of it is all about the individual and what they think is appropriate, and of course not everyone will see eye to eye on these things.