Nexus 5x Parts Repair/Warranty Help

Hey Ozb, I was hoping if there was anyone could help me out here (a bit long),

So about a month ago I started noticing a vibration dysfunction on my nexus 5x. The issue was that it would not work for whatever reason, on every function that would normally trigger a vibration (home button, incoming calls, double tap to open camera etc.). It had worked perfectly for the last 4 months since I have bought it, and it only recently started randomly dysfunctioning. At first I thought it was just a software problem, so I moved on hoping that the next day it would "magically" disappear. And of course, it did not. Another few days passed of me troubleshooting and searching for help online, but nothing came up. The next morning, somehow it started working again. So i moved on with my day, and then again, at the end of the day, it stopped working. I was really frustrated. I tried a full factory reset, to no avail. I believe this is a hardware problem.

A few more days passed of me trying to figure out what made the vibration work, but again, it did not help and I was stuck with a vibration less phone. I called up LG to see what they said, and they said that they didnt know what was going on either. They suggested I follow through with warranty, and just take it from there. This is where my problem is.

I bought the phone via Ebay through Digital World International (yeah, I realised my mistake now) as it was - at the time- very cheap and affordable (i'm a student). I have messaged them and they said to provide them with a video, and then they claimed that through the video, it was unable to be determined what the fault was (Yeah right). Regardless, they followed through with the warranty claim and asked that I send the phone with packaging over to them for repair. Now, since they are based in china, to claim warranty I would have to send it over there with Australia's insane international postage fees. This might fix the problem (if they can identify and replace the faulty vibrator) or they may claim that there was "no fault" and charge me more for return postage and fees for "wasting their time". Oh, and I wont be able to use my phone for that period either, and will probably have to go out and borrow/buy another temporary phone.

Another option is that I purchase replacement parts off ebay and attempt to repair it myself, which also, could or could not work. Although, it is much much cheaper.

So my question to you guys is, what should I do? Do i follow through with the warranty claim or attempt to repair it myself? Also, is there anything else I can do (within reason)? Any suggestions would be greatly appreciated.

I have never had to claim warranty before, and frankly, after this experience, will never buy grey import products again. Thanks.

tl;dr Nexus 5x vibration not working, either claim warranty or repair myself, risks associated with each, what should I do?