Me again, was on my phone earlier, so was a bit brief
You need to look at admission charge as well as fees.
There are four main UK curriculum schools in KL, which have a high percentage of expat staff and students. They are all good schools by British standards.
For Y4, Alice Smith has the highest admission fees, followed by GIS, Desa Park City (ISP) then BSKL is the cheapest
Termly fees are (most expensive first) BSKL, GIS, Alice Smith, ISP.
I imagine that BSKL being the new kid on the block they are still trying to attract bums on seats, hence the attractive admission fee.
I do know that Alice Smith ask for very little extra in terms of text books, trips etc, the other schools do- my friend whose kids are at ISP was asked equivalent of 150 pounds for an overnight residential not 10 miles from school - she did ask for a breakdown on the price and they were making a big profit!
So those extra costs need to be factored in.
Steer clear of Fairview, Tenby School in Shah Alam, Mutiara Grammar School in Ampang, and Sri Garden (not to be confused with GIS- a totally different school) - all claim to be UK International schools with very attractive fee structures. They are technically using the UK curriculum but use untrained local staff, and a handful of expat staff who can't get jobs anywhere else (ask yourself why?), who they treat appallingly, and are basically private schools used by local parents who can't afford the big fees of the major international schools, and they get ripped off as they are drawn to the "UK International" label, and there is really no comparison.