You can get a well built bottom end be it rb25/26 or 30 for around 3k. Drop in a set of forged pistons and rods, thats bumps the price up to 5k. Cams and springs, 6.5k. Add an ati balancer - 7.5k.
Unsure with the 26's but the 30's have issues with more than 7500rpm when making 700hp, the stock girdle needs beefing up.