Another lower priced coilover option is the one from Feal Suspension. Based in the US, can revalve to suit.
http://rallyracingsuspension.com/page26.html
Lance Keeley who won STX at the Blytheville Tour over some very good competition and came in 2nd at the Pro is using those with 7K F/R springs.
Fortune Auto is a good option since they are based in the US, dyno the shocks, and provide good support.
I would take the GC setup, Feal, or FA over the KW V1s/STs, etc. since they have better support in the US.