Also late in,
I only install Rcbo boards if I'm supplying materials.
OP you've had lots of good advice, although I did skip some posts. I'd like more clients to provide materials, one less thing to worry about. If you're still wanting Rcbo on a budget:
BG: not fitted many as I don't like the brand but they've installed ok.
Contactum: fitted more and I like these, not had a problem.
Live: are a bargain but bring a holesaw. I use wiska t&e glands for cable entry and the access for these is below par imo. Be prepared for a struggle aligning front panel and fixing screws, you pays your money etc...
Where budget is slim these boards have been acceptable to me.