I am looking at the 100W ones.

One question. Whats really useful size ? I am looking ebay at RECI 100W Co2 1300x2500mm Flatbed Laser Cutter Laser Cutting Engraving USB, which i assume is around 80W. But hey, around 5000 only. Then tax, extra reserve tube, etc. I started already thinking schemes how to obtain it :-)