i did my build last year, £1200 on bottom end for a 2046cc forged rods, steel rods, arp mains and gaskets.
area six head, t04b ball bearing turbo, modded sx200 manifold, alloy HO inlet.
i had a lot of welding to do and machining to get parts to fit as to avoid spending where i didn't need to.
i reckon on about £3500 on the engine side (already had management and injectors)
around £1600 on mtx75 conversion, custom shafts, 6 paddle clutch and frs box etc.

all in a mk2 fiesta, loads of one off parts/mods done by me to keep it in budget and a compact setup where possible.