Even if you were going to pull the motor to address some other issue (leaking pan rail for example), I don't see why anyone would want to install a new factory piece and be right back where they started. The factory one will leak again over time, it will warp again if over-tightened, it's still made of garbage material, it's still sealed on the inside with a single o-ring...
You don't have a signature so I have no idea whether this next comment applies to you or not...but...
One thing that never ceases to surprise me is the number of people that will spend large sums of money on "optional" or "accessory" type stuff (lift kits, wheels, bumpers, lights, stereos, big horsepower mods, etc.) that will then be unhappy (some very much so) when they have to spend good money (sometimes significant) to do "necessary" work like repairs or maintenance. It doesn't matter if it's a daily driver or an all-out competition vehicle, you still have to take care of it and fix what needs to be fixed.
Don't take that comment the wrong way, I wasn't trying to be a jerk. We literally see it on a daily basis though, guys will roll through our shop in gorgeous trucks, tell us how they use it to tow their ski boat, toy hauler, etc...and then balk at necessary repair costs. It's even worse when they created the problem themselves, by neglecting the trucks "needs" so they could spend the money on their "wants"...and somehow we end up being the "bad guy" for delivering the news (don't shoot the messenger).
Maybe this isn't the situation with you at all, maybe you've got a 100% practical vehicle that you use for work or daily driving. Maybe you actually "need" to drive that diesel (so many people have one just to have one and never tow and don't "need" it) so the extra cost of owning a truck that uses a more expensive fuel (don't get me started), takes 15q of oil, uses filters that are more expensive than the tiny gasser filters, wears through tires faster because of it's weight, etc...is a necessity. Maybe you're on a tight budget and this is literally just a matter where the money is coming from, rather than what new toy you can't buy if you spend the money to do a repair. That being the case, my original point of "what is it worth to you" still stands. If the oil leak isn't bad enough (yet) that you are having to add oil regularly, if it isn't making a mess in your driveway that you keep having to clean up (wasting time and cleaning supplies)...if it isn't really a problem yet...don't do anything. Spend the time saving up to buy our part or planning when you are going to take the truck out of commission to pull the engine and fix it with a new factory part...whichever method gives you the "warm fuzzy" feeling you seek.
On the other hand, if the leak is already a "problem", you have to factor that into what it's costing you. Every time you have to add a quart of oil...$. Every time you have to waste time cleaning up a mess...$. It's already costing you time and money, and the longer you wait, the more it will cost you. How you use the truck also plays into the equation...if you have something else to drive and it doesn't matter if it's down, you are in a very different situation than someone who counts on their truck for work or daily driving. Having a work truck down is a "time is money" situation. Having to rent a car to take your daily driver down is a "time is money" situation.
This was a long post to get to this, but in the end, is $300 really that bad? I can see the debate over thousands (like fixing a 6.0L), but this is really pretty cheap. It's only about 1-2 hours of your time to install it, and you can just move on and not worry about it again.
That's my perspective, for what it's worth. I've had a number of people tell me (some actually nearly yelling at me) that we are jerks, the part is too expensive, etc. Everyone has their opinion, I don't get offended, I simply choose to pay more attention to all of the customers that call us, email us or post online reviews raving about this product because it was fast, easy and a lot less expensive than paying a shop to pull the engine. If you would prefer to pull the engine and use a stock part, more power to you.