It will cost you ~$450 in a real independent shop. Apples only option for repairing logic boards was always swapping whole thing for $850-1600 or up-sell to a new device.
This is my experience too. An unexpected failure on my 2013 mba and Apple suggested new logic boards with no guarantee of fix the problem & recommended a new mba. I literally went across the road and a flat fee of $500 got me going again. He desoldered a few components and replaced with parts taken from a spare mba mobo. Couldn't be happier.
I was a 2015 MBP owner for many years and suffered through being stuck on 8GB of RAM the whole time because Apple refuses to swap logic boards up to different specs than the original SKU.
I only realised later on that the indie shop near me would have been willing to do that upgrade, or perhaps swapped my machine over to a 16GB one they had traded in with a smashed screen.
