There are several different developers and products available in the UK. Some create custom-built products for clients which cost big $$, others make cheaper products destined for the mass market (eg www.sportinglot.com). The developer pay the fees to Betfair, and then they have the right to charge their clients whatever they like. (The client pays nothing extra to Betfair)

All these systems are only as good as the person who writes the specs for them - if you have a flawed 'bot', all it will do is become more efficient at losing your money! But if you have a set system which consistently wins and can be automated, you can buy back a lot of your time...