  Cost estimates for simulations of full QCD with n_f=2 Wilson fermions by
hybrid Monte Carlo are presented. The extrapolations are based on the average
number of iterations of the iterative solver within the fermionic part of the
HMC molecular dynamics, which is closely related to the minimal eigenvalue of
M^+M The cost formula is determined as a product of the scaling functions of
iterative solver and integrated autocorrelation time as function of the inverse
lattice pseudoscalar mass. Timings by SESAM/TxL allow to fix the pre-factor. It
is demonstrated that a 2-flavor dynamical determination of light hadron masses
with a statistical precision comparable to the corresponding quenched results
from CP-PACS can be an appropriate task for a 100 Tflops system.
