£500 - 750 is a decent budget, and you should definitely get something good for that, either vintage, or newer. Something important to remember is that the lathe is not the only cost. While you should try and put as much of your money as possible into the lathe, you will also need some way of mounting timber - a 4 jaw chuck ideally, but at the very least a faceplate, a couple of gouges and a way of sharpening them.
I agree with what people are saying about a club, but it is not essential. I am entirely self taught and managed ok just working things out. It is annoying however when after ages of doing one thing you see a better way, and realise that if you had been talking to people, you would never have gone down the wrong route!
Old cast iron machines such as the myford m8 or graduates are wonderfully heavy, so will do well with heavy off centre pieces. If you want to make large bowls, you will probably be starting with wet chunks of logs (very hard to buy big dry blanks). This needs a heavy machine and as low a speed as possible. 500rpm can feel awfully fast when you start spinning a big chunk for the first time! DC variable speed is the dream, but it is expensive, and a belt based system is ok so long as it has a low bottom speed.
One feature that new machines often have that I really like is a rotating head. This greatly increases the diameter that you can work with, and the convenience. Older machines often have spindles at both end of the headstock, but this needs a chuck for both directions, and generally a free standing tool rest to take full advantage. If large bowls are what excite you, make sure you can grow into your lathe in this respect. I have never used even half of the bed length on mine, and even with a swivel head I always would like to push the diameter a bit more. Remember, a 30cm capacity rarely equals a 30cm bowl in the real world...
My choice in that price range would be a Sorby swivel head lathe. There is one on facebook marketplace including 4 jaw chuck and tools for £750. FB, so may be a scam, but it is a good, (but not too good!) price.