I'm gonna say what you probably already know: don't go to Walmart or Bestbuy. Whatever they have, it's most likely not good

I second the comment recommending craigslist, you can usually find some very good Thinkpads being sold for 200 bucks by particulars, but of course you also gotta do some additional checking about the state of the product. Maybe some local electronics store in your area could have good laptops for sale? Finally, if you're very lucky you may find some company laptops being dumped on the street by whoever had to declare bankrupcy ; this is probably not that common, but a lot more common than one would think