1. I would most definitely not want these to be unlimited. It actually reminds me of something that was suggested before, wanting Unlimited Bolt Scrolls, regardless of the price it's a huge no from my end. ( It raises other things like this to be wanted as Unlimited )
2-5. These suggestions, 2 through 5, seem pretty reasonable and viable. However, for me, options 3 and 4 seems the best way to go about this.
Option 3, is as straight forward as can be; adding them into the convenience store is also a quick fix to this, as they are on the same boat as Aloevera.
For option 4, maybe adding a custom card to get a bit more the way we can farm Box of Sunlight.
From my previous testing on both maps in which you can I roughly got 15 scrolls within 10 minutes in gef_dun02 and 20 Scrolls within 10 minutes at gl_in01. However, I do feel this is completely RNG with 10% drop rates.
The drop rate for this is low and mob spawn for them is low (20 in each map tested with no cool down for them to come back up. I personally would farm them in gl_in01 before for the reasons of; one, the size of the map and two, the map is easier to walk in compared to gef_dun02 (However, you can farm other things in gef_dun02 if you're a hoarder like myself)
While it is possible to get 100, in roughly an hour if you're lucky, they go by pretty quick and to farm so many is really discouraging for most players. There are ways around this, and that is hiring new players or farming players but yeah.
There isn't much concern in BG/WoE, from what I can see at first glance, and the skill itself is better/viable to use on maps with push back to counter classes like LK (Bowling Bash), Champs (Pneuma), and even Profs (Wall of Fog) as stated previously by a more sinx veteran and pvp expert Neo ( @Vergil ). But anyways. +1 on the idea to put them in convenience shop or help boost the chances of them being dropped similar to Box of Sunlight.