Airsoft World or Action Hobbies, probably a few others out there as well. Depends which gun you`re after, some of the clones are in short supply due to problems in China and prices aren`t as cheap as they used to be.
Airsoft Armoury also lists some.
And of course, forum member dog green 1 - Chris at Northern Militaria.
You've got nothing to ein, zwei, drei, vier
And of course, forum member dog green 1 - Chris at Northern Militaria.
Indeed - My Sten came from him. 
I'd second either airsoft world or dog green.
Both are very reputable and reasonable prices.
In fact I got my sten of dog green and not only did it arrive really quickly but it was the cheapest quote i had in the uk. As if that wasnt enough the manufacturers packed a part wrongly and chris got it replaced very quickly for the right one
"I think we are in rats' alley - Where the dead men lost their bones."
