One thing that should be taken into consideration is the cost of scribing. Depending on the 'rules' in place and the availability of gold, scribing can be a minor inconvenience or a major cost obstacle. Some systems try to equate the cost of each scroll with that of the difficulty (level) of the spell AND the components (from 3.5 rule books etc) required, making some spells very expensive to scribe. Other systems adopt a more uniform and less expensive system using a nominal price per spell level and one or two gold for the cost of a blank scroll.
Whatever the case, the dev's should (not saying they will or are inclined to do so) publish a cost table. You're obviously not the first wizard on the block or in this 'world' and making the costs obscure and only discovered by trial and error ignores the fact that in any 'world' this has been done before, LOTS. It would be common knowledge to the wizard class as they hobnobbed with their peers and participated in fraternal gatherings. If this is not the case, then I would suspect that spells in general be acquired in some mystical fashion more akin to clerical acquisition than the 'learned' ways of mages.