Its not really that powerful
You can get geas as spell-like ability or even supernatural ability by worshipping Besmara and becoming one of her Evangelists, which should be available as soon as 12th level. This turns geas into a standard action:
Coerce Service (Su) You understand and can exhibit the blatantly charismatic pull of your goddess, convincing others to aid you even if they normally might not. Once per day, when you attempt a Diplomacy check to bribe a target (treat as if you are attempting to improve an NPC’s attitude toward you by one step) or an Intimidate check to coerce a target, you can use this ability to gain Besmara’s blessing to ensure further cooperation. You gain a +4 sacred or profane bonus (of the same type as that provided by your obedience) on the Diplomacy or Intimidate check, and if you succeed, the target is immediately subject to a geas/quest effect. For as long as the effect lasts, you can concentrate as a standard action and learn whether the target is actively undertaking your orders or actively defying them.
So, for a skill check against a fixed DC of either Diplomacy (for out of combat) or Intimidate (for combat situations) with a DC of 10+HD+cha bonus, which you can obtain a fairly high bonus by 12th level, especially if you are a cleric or oracle, which already benefit from a high charisma.
If you compare that it's a 1/day geas as standard action at no cost, to using a limited wish for 1500 gp, it's much cheaper, and trust me, this isn't something new or unique to Pathfinder.
Limited Wish is vastly more powerful though and the fact that it can make spells that normally have a long cast time into standard actions is already proof of it's power, but that's not a problem with geas, it's a problem with limited wish (and wish). They are very powerful spells.
But if you look at what a wizard can do at 13th level, you have several very strong options too, from disintegrating the target to turning them into a frog, to commanding a group of people to kill each other, to traveling to another plane mid-combat. At 13th, you already have Power Word: Blind, which can nullify most humanoid enemies at that level, especially spellcasters. A lot of encounters ended quickly after a Wave of Exhaustion, or Greater Black Tentacles (black tentacles is a favorite of mine playing a wizard).
The fact that it doesn't allow a save makes geas powerful, but not as powerful as you think, its a subjective effect that can be subverted if you are not careful with your wording when casting the spell. Saying "kill all your friends" will suddenly be met with "f--- you, I'm not your friend anymore" phrases for the duration of the spell if your players are clever enough. Thinking about it, I would have serious doubts about the sanity of anyone saying they are still friends with someone who is trying to kill them.
Keep in mind that the cheapest protection from compulsion effects is a 1st level spell (Protection from Alignment), which won't help if they are already under the effects of the spell (which allows no save), but will prevent geas from working on an already protected target.
