The front unit would be £550.00 + VAT and the rear unit is £610.00 + VAT, they are supplied from the factory with a suggested spring rate, if you wished to change these you have to buy optional springs at an extra cost of around £60.00 + VAT each.
K-Tech Suspension Ltd
Units 1 & 2 Marquis Court
Rawdon Business Park
Moira
Derbyshire
DE12 6EJ
With most bikes I find decent forks make the biggest improvement but with the GS most benefit seems comes from a decent rear shock IMO, I have uprated Ohlins F&R which was expensive but made a world of difference
They do make a difference, but at the current prices they aren't worth it for the difference they do make. Especially for using on the road just at weekends