I purchased my Brother Nouvelle 1500s used for $400. It has a 9" harp space, is straight-stitch only, mechanical (not computerized, so no boards to replace), knee lift, thread cutter, needle threader, needle up/down. I own 7 machines and this one is my favorite. Retail price is $800-$900, although sometimes you can find it for $599 or $699. I haven't checked prices in a couple of years, so it's possible my info is out of date.
Janome makes a very similar machine, the 1600P. It has all the same features as the Brother I listed above, only you can't lower the feed dogs. I have to put a special plate on it if I want to quilt.
To be honest, I think you'd be very, very lucky to find such a machine with a table for $400. I bought mine from a friend who was upgrading.
I think your best bet is a used mechanical machine such as one of these. Put the word out to your local guilds, quilt shops, and dealers that this is what you're looking for. Watch Craigslist and other social media outlets that allow you to search by local, such as NextDoor.