While I've had only about 6 decades of experience with "natural repellants" I've also had access to my grand daddy's book on the subject with his handwritten comments on many he tried.

My personal conclusion, including his notes:

There are a few "natural things" that that can slightly reduce your ability to see the critters but almost none that have much effect on how many of them are around.

First recommendation: Spiders only appear where there's something to eat. Quit worrying about the spiders and try to get rid of the smaller insects they feed on, and the spiders will go away.

If you want to reduce visibility of the spiders and don't like spider guts when you stomp one, a small hand-held vacuum cleaner is a good way to snatch them out of sight. The problem is that the smallest and handiest "little suckers" seldom last long as an effective device, so you need a new one at least every year, and the more reliable ones require getting them out of where you keep them, and finding an outlet to plug them in, and by that time the spider usually is already out of sight.

For the smaller spiders, the insects they feed on are likely to be extremely tiny, and not easily seen. One thing that seems to help is to scrupulously remove every place that might be slightly damp including especially any little cracks and crevices. An ordinary circulating fan directed at cracks where there might be dampness deep down sometimes will dry dampness you can't see to a level where the food bugs (or at least more of them) will leave.

As there are very few natural predators that will eat spiders, the options there are limited to having bunches of little birdies of an appropriate kind flying around in your home (potentially somewhat messy, according to enthusiasts of aviculture) or inducing a family of common small snakes to take up residence (likely to be a hazard for family pets as most are only interested in spiders while they're young, and eventually move on to larger meals).

There actually are few "extreme measures" that are particularly helpful for spiders. One professional exterminater quite a while back informed a former spouse - on her third call to complain about seeing "a spider" -

"There is NO INSECTICIDE I can legally use inside an occupied residence that will kill spiders. The best I can do is hit 'em with a shot and get them drunk enough so they'll follow me out to the truck for another shot.

"I'll spray 'em if you want, but I can't kill 'em. And I'll have to bill you for additional time if I sit out in front to see if the follow me."

Get rid of all the other bugs (that you don't see) and the spiders (that you're seeing) will go away.

While I can applaud and encourage your aversion to "commercial insecticides" there are some, if you select them carefully, that may be effective on the "spider food" with minimal side effects. There are NONE that I've heard of, natural or commercial, that are very effective for use directly against the spiders themselves, with or without all the nastiness.

John