mines only a budget build but ive done it for under a grand just by getting parts when they're cheap.
£500 got me a t25 with manifold, pectal management, gearbox, blacktop head and everything else I needed plus more as a job lot, all I had to do was buy an st170 bottom end for 150, head gasket and bolts for about 70 and a set of driveshafts. im sure ill need more bits when I drop it in but should still be under a grand and hopefully around 240 brake.