How to obtain base rom

So I just received a chinese tablet and as good of a device it is for the $100 I spent for it, the rom sucks and since there seems to be no support for this thing it seems that I will have to make my own custom rom, but in order to do that I need the stock/base rom. Can someone point me in the correct direction to go about doing this. I'm assuming the process can be device specific because when I search "how to get base rom" all I get are device specific instruction. Is there any generic way to obtain my base/stock rom