Here's a simple suggestion:

Make Ice Bolt I for sale from the Imperial Spell Vendors
Make Beginner, Journeyman, and Expert Ice Bolt formulas from the approrpriate Spellcrafters
Make Improved Ice Bolt Formulas availabe for the appropriate Formulatrons, and as drops from monsters

If you have a high-level quest for ice spells that have really high-level requiremts, don't make it for a Bolt spell.