Most repair shops have resources other than iFixit for obtaining parts. Most of these 3rd party vendors have different quality options however they most likely won’t be the true quality that you will get from a genuine Apple part. Really the only way to get genuine Apple parts is to either take the device to Apple or and Apple Certified Repair Shop.
With that said, if you can live with what will most likely be a lesser quality screen (you may or may not even notice a difference) then I would say it might be worth taking it the a 3rd party repair shop. Honestly, I don’t think Apple needs any more money from it’s loyal customers after they have already pried hundreds of dollars more that what I actually believer their products are worth. That’s why taking it back to Apple is so expensive. Apple has to add their own tax to everything.
A few things to be aware of however if you take it to a 3rd party. Check what their policy is if they break something during the repair. I honestly believe that if they break something they should fix it at no cost to the customer. Also, if the home button gets damaged, Touch ID will never work on the device again unless you take it to Apple to have them pair a new home button. If they break that function will they replace the device at no cost to the customer? I would also check to make sure that they test devices before and after the repair so both of you know what’s working and not working. It protects them and it protect you. Finally, do they have a terms and conditions document? If not I would maybe get something in writing stating that if they break the device they agree to fix it at no extra cost to you.