I suppose it depends on your estate - I’ve just done a new will at my Solicitor and scrapped the old one. The cost was £495. Before I did it, I was asked several questions about my ‘estate’ and based on my answers, I think a Charity would’ve expected more than the £495!
Years ago, friends took advantage of a £99 will offer, only to find they couldn’t track down the Company later.
I think it pays to go to a reputable solicitor, especially if there are several bequests, etc. On the other hand, my Dad who had very little to dispose of, did his own on forms he bought in WHSmith and had his neighbours witness it.