Can you buy from a government auction in another state?

Yes. GSA Auctions, GovDeals, Public Surplus and most other platforms let anyone register and bid on lots in any state. A few lots are restricted to public bodies or other eligible buyers, and the listing says so.

The catch is pickup. Almost all government surplus is collected by the buyer from where it sits, inside a removal window that is often 5 to 10 business days. A lot several states away can be impossible to collect in time unless transport is booked before you bid.

Sales tax is normally charged by the state where the item is located. For a vehicle, you title and register it in your own state, using the paperwork the seller gives you.