If you get spend a little more for a quality PSU, it will last through all of your other upgrades. It's really one of the few things that can be totally useful even after changing out your motherboard for the third time with that new chipset required by your next cpu.
That is a certification of efficiency but does not take into account quality of cooling (fan bearing, design in component placement, control etc), especially important in SFF, or of assembly of components. If cost is really such an important factor, I would consider a larger form factor where constraints would not be so costly. It would at least be easier to build a quiet machine when fans can be larger and run a lower RPMs with adequate room to route cabling and facilitate ventilation.