I am looking for a system where I can get Dolby Headphone via an optical input. What would be the cheapest way to achieve this?

[AVus3r]

Try looking at Victor (JVC) SU-DH1 DH surround adapter (£87 from Bluetin) with a decent pair of headphones like Sennheiser HD555 (£55 from Amazon). I haven't used this set-up myself but Victor has had good reviews. Apart from that you have the wireless solutions from the likes of pioneer (Audiocubes) that will set you back £400 for a decent system.