Scour Gummie for a second hand adjustable barstool in the mean time, some are free or heaps at less than $20.
I use mine with the SW 8" dob and its works at all heights very well (I'm a little over 6"), if you find your lower back gets chills, I would strongly recommend one with a low curved back.
Despite the looks they can be pretty light, mine weighs in around 4kilo and is one of the better $20 addons I have bought for viewing.
Most give the height from the seat for max/min heights, if you want to see if they'd do the trick.
(I did a quick scan and stock issues abound, though amazon.au did have a nice wooden chair at $99 out of stock -
https://www.amazon.com.au/Telescope-.../dp/B018ZIWDFS)