I am not a breeder I am a business guy. Paying attention to the market price is important because you need to know what people are paying for your product. However pricing is regional the ultra high end it is not as supply is very very small and that there may only be a few of a given morph in any particular area and finding one for sale in your back yard is unlikely.
Spiders are different, they are common and relatively inexpensive, the price should reflect the availability in your area not a centre 1000 of miles away very few will pay for shipping a spider in some cases it would double the cost of the animal. If you are the only person in your area with spiders then you can charge full market price or even a little extra as if the buyer wants one they would have to pay for shipping. If (as I'd guess) there are a number of spiders available you need to be competitive with your area if they are selling for 100$ and you are trying to get 300 you will still have all of them in 6 months. Just because they are priced at a certain amount in california or new your does not mean that is what you can sell them for in maine. Market price especially of the lower end is regional.