it isn't so much the price difference. A new, OE 240sx fuel pump is still about 200 bucks. Thats why everyone just opts for a walboro. its an easy install and less than 100 bucks.

the part that is such a pain is that the information isn't readily available for the 300zx's as it is for the 240's. A quick google search and you can find just about all of the info you need to do pretty much anything with a 240. A google search for 300's and you find a lot of threads with no answers to them, and/or crappy, contradicting, incomplete, inaccurate information. Its like no one really knows so they just guess and since the "average" 300zx owners are people that used to own ricey civics and crap, their guesses are usually wrong. And the few people that do seem to know what they are talking about, don't have extensive knowledge. I've noticed most 300zx "builds" just use off the shelf parts and kits. It isn't like 240's where people used to try new stuff just to see what happens.
The part that I find funny as far as cost difference goes is that a brand new J30 fuel pump is right around 100 bucks and that engine is the same as the NA 300zx engine. But I can't find anywhere that verifies the LPH of the two pumps to know if they are actually the same. I really don't want to swap in a less powerful pump.

I have a buddy with a walboro in his 240 that I'm going to try to install on my Z to see just how loud it is going to be. I have a feeling it is going to be just too loud.
On my more "purpose built" car, that wouldn't be a problem. Just like MPG and all of that isn't a problem. but on a daily driver, that whine is a deal breaker.