So i am pretty confused on this one on my 2003 maxima as this is my first junker clunker with a hid setup.

Was under the impression the OEM ballasts generally only lasted 5-7 years yet when trying to find OEM replacements online they all appear to be 20 years old while the ones sold by places like autozone are $400 or more each. yet had quite a few people tell me I don't need OEM but instead just need to splice into the harness of the new ballast to keep the d2r wiring that is hardwired into the lens. Was also told I could switch to d2s if i don't mind blinding oncoming traffic. so i figured I would come ask here what the most cost-effective way to get the job done would be.

Only the '01~'03's used that "box" ballast, after '03 they all used the pancake ballasts underneath the headlight. So those are a bit of a "specialty" item, Matsushita no longer makes them and I think there are only one or two companies making clones. If the igniters can be changed out then you can probably switch over to the more "standard" pancake ballasts, but mounting them might take a little ingenuity.