What budget? At 256 bits (and even far less) it's not a question of money. It's a question of energy. We don't have enough energy production to even execute a single repeating adding instruction that bit-flips 256 bits of data registers to just count up from 0 to 2^256-1, and even if we did we don't have computer setups capable of ingesting such energy. Never mind the fact that encryption rounds and result analysis increases the energy consumption some hundred orders of magnitude.