I joined Yorkshire Wildlife Trust - normally £27, so got it for £13.50. Just looked on the website - prices seem to vary a little between areas but not by much.
For our local trust, Norfolk, the full cost is £38 for a couple plus £7 for children, irrespective of how many you have. So, for our family of five, it is pretty good value at £22.50. Have a look at your local trust for prices and what is available. Norfolk is quite good as it is the oldest of the trusts. There is a map with links to your local trust on the website. The wildlife trust here is an umbrella organisation for all the local trusts.
any idea on the actual costs of this. I know there are several options but I can't seem to find any mention of this.
Also comes with a free Swan (see terms and conditions).