I have a Tiara which is the Sweet Sixteen made by Handi Quilter, under the Baby Lock name. Granted, mine is a number of years old, but had less than 500,000 stitches on it when I bought it so it was basically not even broken in. Get the serial number and find out exactly what year this Sweetie was made. That will tell you a lot about how much it is going for used.
You can check on the monitor to see how many stitches it. That will show you whether it has been "never used" or not. Besides, "never used" is not necessarily a good thing with these machines. They are industrial machines and need to be kept oiled constantly. Be sure to oil it before you try it out. Jamie Wallen has a very good video on this so have a look before you go to try it.
Does it come with the kit which includes the oiler, and hex wrench and little screw driver, directions and all that?
Mine came with the Stitch Regulator, which I sold and if you read around you'll see that most people don't use them after awhile, so you'll have to decide how valuable that is to you. Mine didn't come with the extension tables, which are really nice, but did come with an auto bobbin winder which is really important. Does this one come with that?
I paid less than $2800.00 for mine and got a whole bunch of rulers and books thrown in.
So, unless the warranty is transferable, I don't think it's a fantastic deal, myself. I would look around and see what else you can find and make them an offer closer to the prices you find.
And, make sure it comes with all the stuff.
Watson