$400 is a steal if it's in working condition, without regard to the name I think.
Not really, it depends entirely on the machine. If youre looking to buy a K&T (Kearney Trekker) or other "heavy iron" $400 is about the max youd want to pay as its roughly scrap rate for a 3-4k lb mill (BIG = low demand/fewer people putting them in their garage/hobby shop). Similarly, anything with a flat belt drive thats missing the South Bend, Atlas, or other common hobbyist machine company name probably isnt going to fetch much at all. Small horizontals also wont bring much, with Hardinge TM/UMs commonly going for ~$500. Also, any machine that isnt rare, collectible, or worth big bucks restored isnt worth jack if its got decently heavy wear on it. Refurbishing (grinding, scraping, and flaking) machine ways is one of the most labor, focus, and skill intensive jobs you will ever find period, thus seriously BIG bucks to have it done professionally.
Admittedly, all bets are off if a machine comes with a decently large amount of tooling. Ive been to many auctions where massive turret lathes and other machines are sold twice. Buyer #1 buys it and loads out the tooling, then has the auctioneer resell the machine itself to a scrap dealer, with #1 sometimes paying in the thousands, and #2 paying < $100.