you get the g101 off the auto smart guy in the van,if you go to the auto smart web site then email for you local van,they will then send you back the details of the local guy.
I think I paid £60 for 25ltrs if I remember right,
I use it on plastic roofs,gutters etc and find it does a very good job,
I normally mix it down with 1:4 of water,spray on surface and wash off,ive also sprayed on to the end of the wfp brush and then just washed down.
hope that helps