I don't do a lot of certs, but the ones I do are done directly for the LL, not for some creep who wants to pay me £30 after 4 months and 8 reminders so he/she can charge the owner £130.
Doing lgsc's is like selling second hand Skoda's; I'm sure somebody is earning money doing it, but it's not my cup of tea.
And before anyone tries to tell me Skoda is a wonderful car since VW bought them, I know too many Skoda owners to buy that. But apart from that, I'm referring to them because Skoda owners are typically the kind of people that spend ages finding out what the cheapest deal in town is.