A secondhand machine in good condition will save you money compared to the same machine new.
One in poor condition will be a major source of disappointment, frustration not to mention being a drain on your wallet and time.
I had a ML7 but one reason for getting rid was that the 2MT spindle, was too restrictive, since very little over 13mm would pass through the mandrel.
Later 7 Series have 4MT spindle, so will pass upto 29mm.. But may not have power cross feed, and will be costly compared some of the new machines from the Far east.
Was in Arc Euro Trade today, and whilst waiting, took a quick look at a Seig SC4. Looks to be a tiny bit shorter between centres than a Myford 7 (About 25mm if that is vital). Mandrel is 3 MT so will accept upto about 20mm at a guess. Will be about a quarter of the cost of an equivalent 7 Series. Take a look at the spec.
Am merely a satisfied customer of Arc Euro Trade. Ketan and his staff have always been very fair in their dealings, and not just with me. (He gave a lot of support to someone who had major problems, with a lathe that had not been bought from him). Hence I can recommend dealing with them, if they have what you want.
Similar, and larger, lathes are available from Warco, Chester and Axminster, in U K.
If in doubt, buy a machine a little larger than you think; your horizons will expand.
For the past 15 years, my lathe has been a Far Eastern product, with a hardened bed, 5MT mandrel, and came complete with a Norton gearbox, steadies and 3 and 4 jaw chucks. Like the Warco BH600, and Chester Craftsman, of which it is a clone, they will have been superceded by gear rather than belt driven siblings.
Choose carefully, and then enjoy yourself!
Howard