If you look at my recent feedback since coming back in September, (not including the previous 1063 feedback I had) you will see I have traded onwards of 30B or so, that's not including odd sales I do elsewhere too
Each trade either consists of junk trade or wildy drop, all of my mules personally are not level 3, have some combat + mixed stats of others and were previously member and have lasted for several years - Take this with a pinch of salt though, as everyone acts differently to it, my mules hold no more than 500-600M each at any given time, and accept any junk anything from a few runes to actual rune/dragon items