Xbox 360 Custom Hardrives?

Hey, I am going to buy a new Xbox 360, Except it's not coming with a HDD and cause i hate being ripped off by retail i was going to buy one off ebay for lik 20$ in the casing and all but obviously it can't be made by Microsoft not legit just a custom made one with a Microsoft casing apparently my friend said it doesn't work for xbox live when you have to download new patches for games or something can someone please help me out with a proper answer if you have bought a 20$ hard drive from a electronic shop and just used that for your HDD

Please comment

 

I don't see why that wouldn't work. If I remember correctly one of my friends uses a flash drive to save things on xbox and he never seems to have a problem with it.

 

The Xbox 360 HDD on eBay are usually from China, they use laptop HDD and use a software to flash it so the Xbox can recognize it and put it into a Xbox 360 HDD case, one of my college friend has one and he says it appears to be faster than the official Xbox 360 HDD and cheaper as well​

 

Recently(like a year or so ago I think) xbox updated so that you can turn your flashdrive to an xbox harddrive,as I remember most flashdrives work for this and im pretty sure they are way cheaper then official XBOX HDD, as for the 360 HDD case thing, I believe its just a normal harddrive set up with the method I said above, but in a xbox HDD casing


TLDR; Flashdrives work and are cheaper,

 

Ripoff HDDs might get you perm banned from live. Watch out.