I have paid to pitch but not at anywhere near that level! £50 is the most I have paid and I consider it to be about gaining experience of pitching as much as about raising investment (although the latter would be great!). Mostly I have been advised not to pay by experienced investors and entrepreneurs. If an angel network really likes what you have to offer, they will invite you to pitch. It should be as simple as that.
As far as angel networks go, I have to agree with Paul. Angel networks are nothing to do with philanthropy and just about trying to gain above the average returns. Without wishing to plug myself, I have written a blog post about my issues around angel networking here if anyone has 3' to hear my thoughts.