If you are looking for ready-built kit locos then GRS have two "commission sale" items on offer.
One is LNER 0-6-2T Class N5/1 in BR lined black livery. The loco would be historically more accurate in LNER or GCR livery since the Robinson chimney and Ramsbottom Safety valves would have been replaced by a "Flowerpot" chimney and "pop" valves in LNER days. £1495.
Other is a GWR 1361 Class 0-6-0ST in plain BR black livery. £995.
Both look to be very well built and in nice unmarked (as new) condition.
Spec isn't given but I presume both will be track-powered as that is how the kits are supplied.
To convert to radio control and batteries would cost from around £120 upwards, depending on brand of equipment installed. Adding sound would add about another £60.
http://www.grsuk.com/GRS_Kit_Built_GWR_1361_Class_0-6-0ST_BR_Black-M7030 (http://www.grsuk.com/GRS_Kit_Built_GWR_1361_Class_0-6-0ST_BR_Black-M7030)
http://www.grsuk.com/GRS_Kit_Built_Parker_9N_0-6-2T_in_BR_Livery-M7029 (http://www.grsuk.com/GRS_Kit_Built_Parker_9N_0-6-2T_in_BR_Livery-M7029)