Seen a few of these floating around on eBay and Amazon for around 10. Some reviewers saying that they've had to install paperclips to keep the aperture open/closed; I don't fancy doing this to my lenses and would prefer getting some tubes that don't demand modification or risk damaging my camera/lenses. At the same time, I haven't got the money to pay 150 for Kenko tubes.

Has anybody here got any of those listed on eBay/Amazon that do not require DIY modification? Would be grateful to hear some honest, tried and tested reviews

If you're wondering, I'll be fitting the tubes onto my Tamron 75-300mm Tele/Macro lens.