Aloe in my experience is a very good biostimulant that promotes rooting and plant resilience. It's not as good at rooting compared to kelpak in my experience but it offers other benefits like helping to stave off rots. You can find dried aloe flakes for very cheap from a number of organic fertilizer suppliers or horticultural aloe (freeze dried whole plant). Aloe has been used widely in cannabis horticulture and many people use it to root cuttings.
Aside from plant extracts there are a number of products with strains of Azospirillum brasilense which is a nitrogen fixing bacteria that also produces loads of plant hormones. I used the product 'Nero SC' from Impello biosciences to root some old plumeria cuttings I had forgotten to get to for over 6 months. They started to root and regain turgor after only 10 days. I have had fresh cuttings take up to a month to get going. Another company Imio makes a Azospirillum brasilense based rooting gel. Do not over apply these microbes as some strains will over produce hormones and cause a deleterious effect.
I cut my last go-round of willow in fall right before the leaves fall. The tea lasts around two months in the fridge. Mostly the orchids get Kelpak, everything else gets willow tea, and occasionally the orchids get the tea when I'm making up a big batch during the spring and summer for outside veggie garden and flower beds.
Sorry Ray, just saw this. Kelpak is not free. I'm retired and on a fixed income. If I could afford to use Kelpak on everything, I would.
I have a LOT of other plants, both inside and outside. Willow tea is free. Compost is free. Manure from horses is free. Well, horses are expensive to feed but there's no charge for the end result.
__________________ Caveat: Everything suggested is based on my environment and culture. Please adjust accordingly.
I didn't try it myself, but I read on Reddit that people use Epipremnum (pothos) cuttings to promote root growth on other plants' cuttings with water propagation, because Epipremnum is naturally high on rooting hormones (that's why it propagates so easily).
I didn't double-check this, but it's a cheap plant and I think in the worst case it just won't work