As a wizard, would giving up Scribe Scroll and your familiar be a fair trade for endless cantrips? That is, would that be a fair trade for having any 0th level wizard spell (that doesn't have any metamagic applied) you cast not be expended? I think it would be, but I've been wrong before.
EDIT: What would be fair to get it on a sorcerer?
If I am slow to respond, it is because I just restarted playing Skyrim.
"The only difference between homebrew and third-party content is a price tag." -Me, just now.
I'd say either on or the other actually. Given that you don't have cure light wounds (and even then) infinite cantrips aren't gamebreaking. Pathfinder already has this at no cost, so aside from detect magic spam not that much would change really.
Endless cantrips isn't a balance issue. It's a utility/realism issue. Unlimited Light means that you can illuminate the entire countryside within a 100' radius of your campsite, making it virtually impossible to sneak up on you. Unlimited Arcane Mark means you can mark everything. Unlimited Mending means essentially nothing in the game world (once you get above poverty level) should ever be broken. Unlimited Prestidigitation is just weird; remember that Prestidigitation can and lift physical objects. You have to decide whether you're okay with a world where a 1st level wizard - or any level wizard - can surround the campsite in an arbitrarily large number of glowing, floating magically created objects that taste like chicken. What you give up in exchange for that weirdness is of much less importance.
Pathfinder already gives casters unlimited level 0 spells, so I would say it's fine. Pathfinder does modify a few level 0 spells, like cure minor wounds which only stabilizes dying creatures.
__________________ "...I worry that modern gaming is gradually shrinking the wide spectrum of gameplay mechanics into a single narrow red bar with "KILL" written on it sideways. Exploration, navigation, puzzles, platforming, all gradually shrinking away until only one thing remains, being taken by the hand from room to room, moving on only when nothing remains alive in each one." - Yhatzee Crosshaw
You have to decide whether you're okay with a world where a 1st level wizard - or any level wizard - can surround the campsite in an arbitrarily large number of glowing, floating magically created objects that taste like chicken.
This made me smile.
I think about this often. I see two non-mechanical solutions for this:
1) Cantrips can be done endlessly, but they're as tiring as any physical activity. That's why wizards aren't spamming cantrips everywhere, it's the same reasons monks don't hop around senselessly.
2) Magic users think some forms of using magic are "low" or vulgar. Though cantrips might seem astounishing to peasants, spamming cantrips might be seem as a sign of immaturity or bad taste among most wizards and sorcerers.
However, mechanically, why not instead of infinite cantrips use X cantrips/hour or X cantrips/encounter? And if you wanted X more cantrip uses that same encounter/hour, you could burn a 1st level spell slot.
bock! Help me with me homebrew!
The Pathfinder rule preventing ENDLESS LIGHT is that a caster can only have one Light spell up at a time, it winks out when cast multiple times. Nothing preventing you from having Dancing Lights and Light at the same time, though.