Questions about Hackintosh for development

Hello, I'm planning on building a hackintosh, but it's the first time so I have some questions. I need a hackintosh mainly to use xCode, I won't use it to play games or do heavy graphics.

1) Do I need to install the lastest OS (High Sierra) to use xcode or can I install previous OS? If I install Sierra, for example, will xcode run fine for some years or is mandatory to upgrade to High Sierra soon?

2) Is it possible to build a good hackintosh with Sierra / High Sierra (that fits my requirements) for under 400 dollars? I read tonymacx86's build guide under CustoMac Budget ATX but the recommended components are quite expensive.

Thanks in advance!