Where did you find nt1's for $10 more? Well They both work well for overheads but the Nt1's work better for vocals so it's really up to what your other needs are
Hard to say considering myself nor anyone I know has even heard the NT-3s. I'd say it depends on what other mics you might have and whether or not you'll be buying other mics for other applications (even just general) in the reasonably semi-near future.