Anyone had one of these:

£130 on Amazon

or something like this:

£110 on Ebay

I realise they are not going to be like something costing 5 times more but are they decent enough?

Read the description again….. ‘HD’ goes in – i.e. you can plug an HD source into it… but it doesn’t come out – the projected image coming out (the native resolution) is 854×540. Contrast ratio is pretty poor too, you’d want something closer to 2000:1 when the contrast ratio is poor it means light is leaking into the areas that should be black so things look pretty washed out and grey.

http://singletrackworld.com/forum/topic/outdoor-home-cinema

Im guessing the lumens figures on those are similar to the Chinese bike lights.
I am sure I read a review of similar projectors advertising the same lumens figures and they put out around 3-10% off the advertised rating!!