Well last July I bought 20 m of 10mm2 three phase SWA cable for 70 quid from denmans so I would expect 30 m of 10mm2 to be around 105 quid....

My SWA cable is awaiting connection at both ends with suitable coloured sleeving to mark it has single phase, neutral and earth.

one is at the garage end and the other is for the wood shed and greenhouse