If you buy from bitmain directly, it should be safe.

However, there are some things that might explain the price difference:
- if you buy locally, you won't have to pay import duties and import tax
- if you buy locally, you won't have to wait for weeks (or longer)
- if you buy from a local vendor, you *might* have extended warrantee (i don't know if this is the case within the US)
- if you buy from a local vendor, other things *might* be included (like a PSU, network cables, power cables,...)

Do be carefull when you don't buy from bitmain directly: there are a lot of scammers out there!