cheap compression bag or stuff sac alternatives?

[Lush]

Has anyone come up yet with a cheaper alternative then buying commercial compression bags? I use them for any clothing, my sleeping bag and tarp. I like to have some more bags, but they are quite expensive. Very strong though, which is needed.
Just curious, there might be people that use something else as a stuff sac. It must be strong and efficient though.
thanks

 

[alpha_centaur]

I use the rolltop bags from alpkit which are, actually now that I think of it, not that cheap.

 

[saddle_tramp]

try the car boot sales, ive found 3 this summer. Nothing special in quality, but then none more than 50p