Except they're not a shop? They don't sell directly to the public and therefore probably don't actually have retail prices. Only wholesale or trade. Try one of the online retailers or something. Personally I'm using Britpart airsprings and am quite happy with them. Didn't like their shocks so after a while changed to Boge which I think are OEM.
I replaced mine with Boge OEM from Island 4x4 recently:
Front Shock Absorber (Boge) x1 STC3672 G Island 4x4 - Specialists in Land Rover and Range Rover Parts and accessories for all models. UK and worldwide mail order.
Rear Shock Absorber (Boge) x 1 STC3671 G Island 4x4 - Specialists in Land Rover and Range Rover Parts and accessories for all models. UK and worldwide mail order.
Less than £100, including next day delivery, and their courier always texts in the morning with a 1 hour delivery slot (round my way anyway), and they've never got it wrong yet.