If you're patient you can get a good deal second hand. I sold my Buescher 400 bari on eBay a while ago. It was a late 1960s/early 1970s model with big bell. It was battered and bruised, but played a storm, with a huge, roaring tone (Jules can confirm, as I bought it off him). There was quite e lot of interest, and it went for £670. I think that represents good value for money, and I've seen similar horns from time to time for the same sort of money. If you buy a super cheapy for £900, in five years or so it'll be worth less than half that. If you buy an old but good sax for, say, £750, in five years it'll be worth £750.
Incidentally, I only sold the Buescher because I fancied a Bauhaus Walstein one, and got one for a very good price, second hand but essentially unused.