I’m curious to know more about why the e/OS device cost more than the regular Fairphone Gen. 6?
What is also the difference between buying an e/OS preinstalled Fairphone Gen. 6 vs installing the official build on your phone yourself, and then locking the bootloader after? Is that not the same setup as if you buy one preinstalled?
There is no difference between preinstalled and installing yourself – if you install the official version of /e/OS. Apparently neither official nor community are already available for download though.
And the higher price: 2 companies want their time paid.
As to whether it’s worth to spend the extra 50 € – all depends on how comfortable you are with doing it yourself. I can attest that 2-3 Fairphoners from my local community who did not feel that technically savvy were happy to spare themselves the hassle and bought a Fairphone with /e/OS pre-installed.
You can also regard it as a donation to the e-Foundation.
That all makes sense, thank you for the replies. One other thing, does anybody know if installing e/OS yourself voids the warranty on the phone? Maybe it only with full warrently if you buy it with e/OS?
Regarding donation to e-Foundation, I might be misunderstanding the development of e/OS, but is this not a price related to work made by MURENA for the e/OS on Fairphone? I also would probably subscribe for their services so they should not worry about not getting revenue that way, at least from me 
When you brick it during install you have to pay the reinstall at FPs repair center.
Else to get FP support so far you need to revert to FPOS to check if the system is causing the issues before sending in for further diagnostics
Edit: most recent discussion
If you buy from Murena, they have their own warranty in place, and they will handle support.
At least they are prepared to do it, you might still contact Fairphone if you wish, but what @yvmuell said will apply.
There’s more info available here (when scrolling down) … Murena Fairphone (Gen. 6)
I bougt through Murena. We need to support their mission as well as Fairphones IMHO. Besides, I’m unsure if the bootloader will lock again after manual install? With a pre-install I felt more sure 
Specs say yes, but users would have to follow the install instructions (still to come as of now) to the letter.
I tried out adding e/OS on my Fairphone 3, and there I could lock the bootloader after the installation.
It’s depending on the phone model, but Fairphones have a track record of offering the possibility.
Lately it is also depending on the /e/OS build type (it wasn’t always this way). If the phone model offers the possibility, only /e/OS “official” builds are relockable.
Here they are … Install /e/OS on a Fairphone The Fairphone (Gen. 6) - “FP6”
I can confirm that the bootloader will lock on the fairphone 6 after manually installing e os. Be aware that applying the lock will trigger a new setup process so lock it right away.