The spray that my dad used for mites on his tomato plants is 30% vinegar and 70% water.
I used a roughly 1% vinegar and 5 percent lemon juice (was already in the spray bottle) with a roghly 94% water.
So far it seems to work fairly well. I have only had a couple mites left today on the sensitive plant and the other plants I have sprayed with it seem to be mite free. Also my marigolds that were infested this morning are greatly reduced in visible mites. I sprayed them just a minute ago with an increased percentage of vinegar.
If you ever hear that mites wont do much harm to your plants do not believe them. It is true that a small number of mites will not kill a large and healthy plant, but they do not stay a small number of mites. They spread. What in my case starded out as a very small number of mites has in 3 days (which by the way it only takes about a week for them to go through a generation) easily quadrubled. I went from 2-3 known plants to easily 10-15 hard hit plants. They killed fairly healthy plants in 4" pots in 2 days. They have changed a healthy marigold in a 5" pot to a struggling to survive marigold in a day or 2. These things are bad. Another thing about them that is very bad for home gardeners is that once they have become intraduced into the plants you have indoors it becomes virtually impossible to completely eliminate them without removing all of the plants from your house for 6 month to a year. That is bad. You see mites can live for a long time without eating so that you can remove all of your plants from indoors for 2 weeks and then bring new plants inside and within a few days the mites will be as bad as ever.
I will try to do the virtually impossible and eliminate the mites without removing all of my plants indefinately.
Especially since I plan on doing a new rotation of plants once I remove all of the old ones destined for outside.
On a side note Basil seems to be very mite resistant.