The Chinese lathes are not so cheap these days, and with old iron, you'll need to be able to check for wear to the various slides and spindle. This means either having access to a friendly machinist or spending a few weeks researching what to look for.
Judging from your initial post, you're looking potentially to do larger stuff than model engineering, so the maxim 'Get as large a lathe as you can fit' definitely applies here.
Lathes.co.uk has a useful section on looking for a first lathe. If you can squeeze in a Boxford size or larger, you won't regret it. Other models to look out for are Emco V10p or 11 (which often come with a useful vertical milling attachment), Raglan 5" (Underpriced for what you get) , or Myford 254s, a fantastic lathe that doesn't seem to suffer from the huge pricing of Myford's smaller models, and tend not to be too worn.
My preference would be for old iron due to its superior quality and stiffness (with the caveat that you avoid excessively worn ones). The posts above are spot on - expect to spend the same amount of money again on accessories and tooling over time. It's worth pointing out that accessories for Myford are relatively cheap, Emco and Boxford accessories are expensive, while Raglan accessories are in the hen's teeth category, so try to get a lathe with accessories included - at least some of: 3 and 4 jaw chuck, fixed and travelling steadies, faceplate, vertical milling slide, Quick-change toolpost and holders.
If you go down the Chinese route, I'd recommend Warco or Arceurotrade - they have an excellent reputation for customer support.
Finally, take your time and be patient. Read the threads on the Model Engineering forums, watch some YouTube videos, and do as much research as you can to avoid ending up with an unsuitable or knackered model.
