Think Tank used to make one and it is really good. unfortunately they seem to have lost interest in it along with a few other tripod based products. it was called the "Big Stick" bag. i have one.
Try to find a Think Tank Bazooka. I got one for free from Think Tank about two years ago when they had a promotion buying a rolling bag and getting a free item (value of approximately $15-$25). I asked if I could get the Bazooka (it sold for about $50-$60) instead and they agreed to my request. Shortly thereafter, they discontinued the Bazooka. A great bag to hold my Monostat Tripod w/RRS monopod head. Good luck with your search.
this is for the monopod not the tripod. just a little overkilll. i didn know yes the bazooka too is discontimued. they seem to have a short attention span for some things. you do mean your monostat monopod and not tripod oi don't believe the make 3 legged versions right?
i think thats why they called it Mono(stat)