yeah of course. All the shuttering was spare wood lying around my shed or garden and so were the bricks and paving slabs so no cost there. I also have a plasterers float and various tools etc already.
The size of the extension is circa 2' 6" wide by 6' long by 6" deep (sorry it's not in metric) and took 4 bags of cement (£20) plus 16 bags of ballast (£36) to fill.
The greenhouse was free too so total cost was nominal. Don't think I'm missing anything.
You might need to hire a mixer cos this makes it ten times easier but if you can beg, steal or borrow one that is the ideal result.