Double of what? Tumbling?
I don't see the need to use it on pistols or bolts. Does anything really need to be that clean? And once you get all the lubricant and protectant washed away, you need to dry it and let the lube soak back in.
I had a harbor freight model before I started reloading. There are recipes for homemade solutions that work for brass, but I use the Hornady stuff. A batch of solution seems to only work for a single load of brass, but that could be the poor quality of my machine - which has never cleaned anything other than brass with much success. It is nice to have brass that is clean on the inside as well as the outside, but it is also a lot of hassle to deal with the toxic materials and the wet brass. I could easily see myself giving up on mine.
If you only do a little shooting, and you want it to be very precise, then ultrasonic is the way to go. If you want to do larger quantities of standard range ammo, then tumbling is easier. If it needs to be easy and precise, then I would save up for stainless tumbling.