hi dan
i'm new to this forum and this is my first post, but please don't laugh
i ( being skint all the time ) made up my own gutter vac system for around £150.00 all in.
it doesn't look very pretty but works a treat
the tubing i used is 51mm downpipe from b&q it's about £5.00 per 2 metre length and slots together, i also use the angle connecters to make it drop over the gutter.
you can add more lengths for additional heights but is a bit flexible the more you add, howver cos it's only plastic you can drop it into gutter to move along and not worry about wieght.
to stop the tubes spinning around i just put a bit of black duck tape aound the joins,
simples but not pretty
brad