I bought a Sears/Atlas lathe, used, in 1970 for $200. It came with 3 and 4 jaw chuck, faceplate, MT1 & 2 centers, metal stand, a full set of lantern tool holders, and a full set of change gears. I have used it heavily for forty years. I have replaced the motor, the 3 jaw chuck, the lead screw, the half nuts, the cross feed nut and rebuilt the back gear assembly, the compound feed, and the jack shaft over the years.
The issue with the Atlas lathe is replacement parts. Many parts are no longer available and wear happens. While it is possible to make replacement parts, that can be difficult with limited resources.
Unless the lathe is cherry, I would think $450 is a bit much. Pricewise, you are starting to get into the realm of other options. Having said that, looking at Craigslist and eBay, I didn't see any great deals. Two years ago, I went with a new Grizzly rather than look for a used deal. The reason was I didn't want a restoration project. While the Sears/Atlas lathes were American made, they still have wear issues and buy a used lathe is leaving you open to them. While I am sure there are lathes out there owned by a little old man that only ran it after church on Sunday, many of them have seen much use and abuse.
It seems that e-Bay and Craigslist sellers have fairly well raised the bottom of the pricing range. If you are willing to wait, watching for auctions and estate sales is one of the better ways to find a real gem at a low price.
BTW, the 1/2" is the spindle bore, not the spindle diameter.