The Magic Item Compendium introduced a rule where you could add a static bonus to an activated item without paying the 50% surcharge for multiple abilities in one item, because otherwise no-one* would use all the cool activated items in the book. I also believe the slots allowed for the bonuses were a bit more permissive than the standard stat bonus items.
* No-one who can control their equipment that is, which after all was the assumed default in 3e.
Yeah, that was a very welcome change which unfortunately went unnoticed by most people, simply because it came so late in the life of the edition (and wasn't ever added to the SRD). Likewise, it was an offshoot of the MIC's larger goal of making magic items cheaper overall so that PCs could afford to get some of the "sexier" stuff instead of having to spend everything on the useful-but-boring "
Big Six."
Personally, I combine that with disregarding footnote 3 in the "Table: Estimating Magic Item Gold Piece Values,"
which says "If a continuous item has an effect based on a spell with a duration measured in rounds, multiply the cost by 4. If the duration of the spell is 1 minute/level, multiply the cost by 2, and if the duration is 10 minutes/level, multiply the cost by 1.5. If the spell has a 24-hour duration or greater, divide the cost in half."
This footnote not only doesn't exist in 3.0, but none of the magic items in 3.5 follow this guideline, at least as far as I can tell. Just look at the
lantern of revealing, which is nothing more than a continuous-use
invisibility purge spell (duration of 1 minute/level). It costs 30,000 gp (spell level 3 x caster level 5 x 2,000 gp), ignoring that footnote 3 says that its cost should be doubled for having a 1 minute/level duration.
Footnote 3 was added to 3.5 for the specific purpose of nerfing crafter PCs (and PF1 kept it because it didn't know any better), and the game ignores it otherwise.