you can get a new flyye RAV (same design, just rebranded) off of landwarrior for £140 but in ranger green, got mine in OD second hand.
i decided on the RAV because from what i understand UKSF use them, and i want to try and keep as british as possible (no comments on the M16 please, mainly because anybody who see's it wouldn't be able to accurately name it anyway).
i like it because it's very easy to get off (easier than a RICAS), and it's very adjustable (i've got a 45in chest and 28-32in waist (depending on hunger) and it almost fits me like a glove).
i do not recommend them to anybody smaller than 5'5 or with a chest smaller than 35in, mainly because it was designed to fit big soldiers, and it'll need a lot of work done on it to get it to fit smaller sizes.