I would love to have a brachiation ladder for my daughter....but there's simply not enough space in the flat for one
....I'm currently reading Doman's book (How to teach your baby to be physically superb)....and he does mention the numberless benefits on having one, and ultimately teaching your child to brachiate independently....but he also emphasises on the brachiation as 'a means of life' for the family members...and to be honest, I don't see myself (or my husband coming home after a tiring day at work) to brachiate as much as we should, in order to entice our daughter....
You mentioned you live in UK and can't get it for less than £350?....there has to be a better sollution!....have you tried talking to some self-employed (and very skilles) carpenters?....I'm guessing (only guessing) that they'd be willing to build it for less...