Doonez, I'm currently chasing a liner for a RS1from a shop in Newcastle OZ that purchased a ESS and had old stock. Rang the owner last week and she has boxes of this stuff at home, has not rung back, which is typical!
I purchased 2 RS1 boots and an adjustable rtp 2 years ago and am after another adjustable rtp and liner for a boot. This is assuming that the RS1 would suit your needs.
What size are you after? I'll see if they could be bothered to sell, as there were quite a few sets of RS1 boots and other slalom ski stuff. Their shop sells skate and wake stuff.
I have a 2009 Radar Senate C, RS1 and adjustable rtp and have never skied or seen a slalom course and am a total hack, but love skiing.
Cheers,
James