After experimenting with some cheap LED strips meant for accent lighting on cars, I did some 'proper' research and settled on the flexible strips of SMD 5050 LEDs. This is an excellent page describing the 5050's vs the 3528 type: http://ezinearticles.com/?All-About-LED-Strips-4---The-Eternal-Debate---SMD3528-Vs-SMD5050&id=4670120
You want 5050 LEDs, preferably 3 to each 5cm / 60 per Meter, waterproof (they are covered in a flexible clear plastic and with a adhesive backing.
I got a 5M strip plus power supply from a seller on eBay. Total cost was UKP 50.00.
The LED strips can be cut every 5cm (or 3 LEDs) and are very bright. 5M of LEDs consumes approx 3A (36W at 12V). This is less than the 4 flourescent strips they are replacing.