I have this quite often (most of the stuff my company has not been done before, or at least not properly/usable; for good or for bad) and I get this paralysis sometimes (more in the past than I do now). My mental way of solving it, is to imagine a product that does something similar to the actual 'perfect' solution, but does it far more crappy. Simply put; I make a shitty prototype first (with the thought that the perfect thing will come 'some time' after) that is not perfect. Often will transpire that this shitty prototype is as close to what we set out to do as we can get without unrealistic spending and effort and we leave it at that (we refactor it before launch though). This takes away my anxiety about 'finally doing the perfect' thing.