A good low A Bari will run at least 2000 in just average shape. I bought a Yani 800 for $1500 a few months ago and had to put another $500 in it. You could easily spend $2500 on a used horn. Again think Yani, JK, maybe a rough Selmer, or an average shape Yamaha 61/62.
If you are willing to go B flat instead of Low A you will find better prices.
If you are willing to go B flat instead of Low A you will find better prices.