I purchased a 128GB SD card from ebay, for $10. At this price it pretty much had to be a lower capacity card that's been programmed to report greater capacity than it really has. Given how good ebay's buyer protection is I was curious to see how one of these preformed. Man, it's junk.
Delivery was quick, just 3 days. The package is so generic it doesn't even have a capacity printed on it. You have to look at the microSD card itself for that, which as advertised on ebay says 128GB. No speed listing or anything but I will say it was a very easy to open package. So in that one way only, it was superior to what you would get in the store.
Windows recognized it as having 125GB of space, A somewhat odd compromise between marketing GB (1GB=1000^3) and real GB (1GB = 1024^3). FYI a real SD card marketed as 128gb has 119 real GB. Since we don't expect it to have all that space anyway, who cares. So I tried writing just 1GB to it. Write speed quickly dropped to 1MB/s, and then failed completely at about 400MB! I had to reinsert the card to get windows to see it. Interestingly, it now claims to have a 55 GB file on (I've heard of hardware that employes file compression but never file expansion!).
Unsurprisingly, the 400MB that did get written were highly corrupted. I got tired waiting to see how much was actually good, since read speed was just 65KB/s! I mean, what is that? Class .0001? After reading 280MB, only 60mb of the data "written" was stored.
I tried the same trick I used with my
other fake SD card and added a dummy 500mb partition to the start of the disk so that the real file system would start at a later, perhaps better functioning region of flash memory. But that failed even worse, with only 80MB "written" before the drive became inaccessible.
So in conclusion, this generic SD card is complete junk. I paid $10 for "128"GB, but got perhaps .06GB. At that price ratio, a full 128gb would cost $2000! So that's a pretty bad deal. Of course, I asked for a refund, but even at $0, .06GB isn't worth anything.