The next time around only allow the player access to the most basic level of spells from vendors. That would be any of the Novice level spells in Skyrim. All of the higher level spells should only be available via quest reward, or the occasional find within a dungeon. Other than providing a greater sense of reward, this would help with other aspects of the game at the same time. For one, it would help to fill out quest and plot lines within guilds like the mages guild where acquiring new spells for reward and loot, as well as testing ones skill in magic would make sense. That really doesn't exist at all in the current mages guild in Skyrim, where even having skill in magic is almost unnecessary to begin with.
The great sense of reward that comes with finding a new and unique artifact shouldn't be reserved for just those who use armor and weapons. Making unique and powerful spells that can be found in the depths of the most difficult dungeons is great fun too! This is also true for the more regular spells, just as it is true for the less powerful weapons and armor. All in all, the spell system in Skyrim is a good start to making magic feel more rewarding for spell casters, but it still needs a little more work before it can be a truly rewarding experience to play as a mage.

