Depending where you go around here are what you'll pay. In the off chance I'm paying for air (my club has a compressor. air fills are "free"), it cost me about £7 for my twin 12s. The inland site where i get a majority of my nitrox fills, it costs me £10.26 (I'm a member. and in the winter, I pay around £5 as they send out vouchers in the newsletter every month. I even paid 26 pence once). If I were to join the nitrox club at my club, fills would cost me about £4-£7 depending on the cost of o2, plus a £20 one off joining fee and £25/year that goes to maintaining the compressor.
