There has to be something unique to your installation. Injectors are generic for the most part and it usually comes down to the connector and capacity. Nissan may trump this with some novel fuel rail configuration that requires extended tool/skill sets to refit them.
I'd contact a fuel injector rebuilder/refurbisher for the straight scoop. Then I'd find a cheap set on ebay ..have them refurbished, then installed by a qualified independent.
Unless you have to jump through some major hoops to get to them, injector R&R is pretty simple. I've done it a few times and I could never afford the costs you're confronted with.
That all said, I've never truly seen a failed injector (I'm sure it has happened). Just one that's fouled with fuel residuals. Gumout Regane COMPLETE - Amsoil PI, Techron CONCENTRATE - a couple of tanks, back to back (as directed) should clean up any injector.
Can we get a year/engine/symptoms that caused you to seek service?