Retrofit Roman blind motor?

[Watchman]

A kit to convert our Roman blinds from manual to powered seems to be at least £150. This is for a motor installed in the headrail. I've tried an external motor that utilised the ball-chain but it looks crap, is very loud, and relies on end-stops that can slip relative to the blind position.

I'm after a headrail type of motor but I wish to convert a number of them in my house so >£150 a time is 3x too much to even consider.

So... is my Google-Fu rubbish and can you find a better option, or is that the price you have to pay for quiet automated blinds?

I have LightwaveRF already, and intend to use that somehow to control the motors, assuming they come with some form of adjustable end-stops.

[Watchman]

For £50? Where?