It has to be marketed properly to make it worth the investment, there are companies that only do this so the work must be there to be had. i would be looking more like the 1.50 to 2 quid a metre price range, but depending on area it could be more. Also offer the extras of weed killing and sealing, they look great when finished...
The weather plays a big part on block paved drives as need sanding when done and has to be totally dry...