Chosen Solution

Could I be able to replace my sim card reader in my iPhone 6? I went to the apple store and they said that they wouldn’t be able to replace the reader, just the phone for $299. I was wondering if there was a cheaper alternative like replacing it myself?

Technically. It isn’t usually a diy thing. I would mail it off to iPad Rehab

As @theimedic suggested, it is better to mail it off for repair and is not a DIY job and as Tony suggested, it is unlikely the reader unless you have damaged it in some way. If it is not corrosion or damage, it is most likely a Baseband IC issue. Are you getting “Searching” (No Service)? What issue are you having and a little background on what happened to it? Yes, it would be cheaper for repair than Apple replacement.

You can replace it yourself if you have the right equipment but you have not explained the fault. It is highly unusual for the sim tray to fail as its simplicity is for making contact with the sim only. Only for corrosion would I look to the sim tray as the fault

I have this same problem and im also looking for answer. My phone is not reading the sim card.

I have a iPhone 6s the battery exploded inside of it. I have restored everything everything works except it won’t read my SIM card and the only noticeable damage is at the SIM card tray at the back of it how can I replace it?

No service or no sim can sometimes be fixed by just cleaning the sim reader, some isopropanol and a tooth brush is all that’s needed most of the time. Also check the six sim pin contacts are standing nice. Next step would be to hang a charger port in with the lower antenna connected. If still no luck then a reset of network settings, then an iOS update. After that then it’s a board level repair most likely.