suggests you check with the srd20 for example before proclaiming that. it's rather hard to do voices properly with foot in mouth.
from the archmage listing for example:
Spell-Like Ability
An archmage who selects this type of high arcana can use one of her arcane spell slots (other than a slot expended to learn this or any other type of high arcana) to permanently prepare one of her arcane spells as a spell-like ability that can be used twice per day. The archmage does not use any components when casting the spell, although a spell that costs XP to cast still does so and a spell with a costly material component instead costs her 10 times that amount in XP. This ability costs one 5th-level spell slot.
The spell-like ability normally uses a spell slot of the spell’s level, although the archmage can choose to make a spell modified by a metamagic feat into a spell-like ability at the appropriate spell level.
The archmage may use an available higher-level spell slot in order to use the spell-like ability more often. Using a slot three levels higher than the chosen spell allows her to use the spell-like ability four times per day, and a slot six levels higher lets her use it six times per day.
If spell-like ability is selected more than one time as a high arcana choice, this ability can apply to the same spell chosen the first time (increasing the number of times per day it can be used) or to a different spell.
http://www.d20srd.org/srd/prestigeClasses/archmage.htm
given sp or spell points are an alternative ruleset to spell slots, as they are easier to scale for altered encounter density, no, cost in sp isn't the defining point.
the sla's we get do not take a spell slot. are not generally selectable, pull from sp pool instead of having use restriction based on preparation level, work in antimagic fields, and more. so they aren't quite spell like abilities, and aren't quite spells, and aren't quite quite class abilities. they are in many ways more like duckbill platypuses, then the other things i listed.
as to rendering them in the fashion the thread starter indicated. no. just no. no drawn out convoluted wall of reasoning and rationale for you. my first thought was hopefully noone will dignify this with a response. they have, and now i have.
if you cannot count the ways this would be broken, or valueless comparatively, then you either lack sufficient digits to count on, or are not trying.