I recently asked RC conversion question to some retailers, and the replies I got:
GRSUK will charge £300-£400 on top of loco price, they are able to convert most locos (as long as space is available inside the loco)
TrackShack can only convert Baguley and will charge £500 (incl loco). This doesn't seem a bad price (compared to Roundhouse price) but Baguley is out of stock at least till next year!
Peter Spoerer has only one RC loco (Class 03 diesel) which costs £750 (thus approaching Roundhouse price)
Other dealers have not reverted back.
I have seen the Stainz RC battery loco on GRS site. But as this is done via tender it didn't interest me (if I do it myself then OK but won't pay that much for a tender conversion).
For me the main difficulty is to open the loco (once I guy one) to remove all the power pickups (and then reassembling it back). As long as I can grab a proper donor loco, I am ready to do the experiment.
I could find lots of LGB locos on Ebay but most of them either comes with DCC/MTS (making matters more complicated) or old locos without power socket.
But anyway, thank you guys for all the support and encouragement.
My main frustration is that even in 2015, when we are talking of driverless cars, trains, aeroplanes we are unable to buy a simple RC locomotive for garden railways!
There is one from Playmobil @ £100
and the other one from Roundhouse is @ £1000
The market is crying for something in the middle.
PS: Why the Newqida loco is no longer available? Is it a good hauler? Are the wheels made of metal or plastic?