We now use a mix of geranium and lavender essential oils diluted in a carrier of jojoba oil, applied to their collars with a small spray bottle every few days. I love the scent of geranium and unlike the gross commercial flea liquid I am happy to carry the dogs against my skin right after applying the oils. So far we have had no problems, but I am not sure how effective the oils are against ticks so I still examine the dogs after walking through longer grass or forest.
I bought the oils and spray bottle from Muji because I wanted to make sure they were 100% essential oils (not "perfumed oil"). The initial outlay was quite expensive, but since we only need a few drops of each essential oil in the carrier it should work out cheaper in the long run. With any luck the height of bug season is past, but next year I will try using the oils on myself as well as the dogs.