Here is a pneumatic of 40 cm going cheap, the Omer "Tempest".
https://www.ebay.com.au/itm/Omer-Te...987792?hash=item469cf49e90:g:bIAAAOSwpBNddIPa
These guns all come from the same suppliers and are all clones of the "Sten". Hang Fung Industrial copied the "Asso" which is itself a copy of a "Sten", but the Omer will have a more believable warranty, although you hope that you never need it. Rock bottom price for a "Sten" clone is 100 bucks, but rock bottom is what you get in the shortest guns. You can buy the Asso 30 for 100 bucks, but it ain't worth the money as you might as well hunt with a toothpick (well not really, but you get my drift).
At one time Salvimar were selling at an out the door price of 99 bucks for their Vintair 35 cm, but that bargain price seems to be now over and the guns were slapped together with no fettling of the parts, although with some time on your hands you could have fixed this with a sharp Exacto knife. I bought two for my nephews as future fish stickers.