kinda weird in ways... my current shop that i go to, they know i'm a DIY and they work with me in most cases.
I had to get some EVAP parts from nissan. I picked up 3/4 parts from the Junkyard. Last part i was not able to get so they told me $80 for the part from local dealership. I didn't have a problem because i felt it was a fair price because it will be done same day and etc. I got home and looked up prices for giggles. I was no able to find that OEM part anywhere from the many discount nissan dealerships online for less then $125. I called my local dealership and they wanted $175. There is no aftermarket part available for this part, i've looked. So apparently they can sometimes get it for cheaper then you can if they have a good relationship with a certain dealership.
I know in the case of Advance auto, list price for us might be $100, we use a coupon code that everyone knows about get 33%. Makes it $67 our cost. But they sell it to the shop for $50 and they mark it up 40% to be $70. This is some cases i've seen and talked to some parts people. While we might pay $3 more, we have that extra warranty. If you bought a part in and it fails, the shop will say your on your own, or best case they give a discount the 2nd time around and make your buy their part. Now if they bought the part and installed it. You should not pay a dime.
An intake boot in 90% of the time is almost always a DIY job. It can be as simple as 2 band clamps on a 4 cylinder that is right on top. Or maybe a little elbow grease for the ones that hide their throttle body.