In this case I would disagree with you Nathan because as a buyer what you are concerned with is how does the item perform. If the product took one month to be produced or one month plus two months shipping time to reach the store does not really matter to you.
For example, if you go to the store and buy something ( say a saw ), you only really consider how well does this item suit your needs compared to the price. If there are two saws that are available and do exactly the same job and identical in ability then you are not going to pay more for one because the person that made the one saw considers their time is worth $40 per hour while the other considers their time is worth $20 per hour. You are going to buy the cheapest saw that does the job.
You rarely will consider things in terms of "brand" name unless there is a special history of reliability to back it up ( what is sometimes called goodwill ).
The time value is really a factor of the producer. The great master with arts that allows the production of an item in 1 season as opposed to another in 2 seasons gets the benefit of producing more in less time. His skills already are the compensation. His skills also are already compensated by being able to produce items that another could not produce.
For example the magus with a level of 40 in an art could write a book in an art at the level 20 that a magus with a lesser skill could never achieve. The suggested complensation of the ability to study longer from that text means that the greater skill is already being paid.
The same goes in the production of charged items where the higher skill is going to produce more charges which means more value is included in the suggested price.
The greater skill rewards the creator in more efficient production time and the ability to produce items that others can not produce ( like a lesser enchantment with a big extra penetration bonus ).