I'm running an AD&D 2e campaign, and one of my players is a wizard. The party is currently first-level (ranger/wizard/cleric/rogue) and has recently arrived in a fairly major city. I don't want to just let them buy spells, because it simply doesn't feel right thematically.
However, at the same time, I can't seem to come up with a good way of distributing scrolls without pitting the party against NPC wizards. While this is certainly an option, I'm nervous about such a proposition-- a wizard capable of casting even a measly Magic Missile, for instance, would be able to cause serious trouble for a first-level party. (1d4+1 damage is rather significant when you have 4- and 6-HP PCs!) If I were with a group of experienced players, this likely wouldn't be an issue, but at least two of my players are first-timers, and I'm worried about scaring them off with an "unreasonably" powerful enemy. (One of them hasn't player anything closer to D&D than Skyrim, for context, and the party decided to walk away from three plot hooks because they seemed dangerous.)
So, with this in mind, what is a reasonable and appropriate way to ensure that wizard PCs can gain spells without placing the party in a level of danger that would be deemed "unreasonable" by novice players?