An automatic feeder is not a usual feature on an engine lathe. It's more something you would fit to the lathe when and if you find a need for one. Or when you say "automatic feeder" what feature is this you're asking about? A feeder usually suggests a collet chuck with a floating handle on the outboard end so you can feed long lengths of bar through and advance it a bit for the next part. Or are you referring to the the usual automatic carriage and cross slide travel that moves one or the other under power?
If that is the case and you're actually just looking to find a machine with the usual power feed of the carriage and cross slide then you'll want to find a lathe with a quick change gearbox. Otherwise it's awkward to change out the gears to get the right feed speed. Be aware that a lot of the newer models have a speed changer that is not a real and proper quick change box. Those are rather limited and rely on a combination of gearing changes on the back side and then selecting "multiples" with the gearbox. So rather limited compared to a "proper" fully featured QCGB.
You're likely looking at finding a 12x36" or perhaps a 13x40.
Price wise it's hard to say. New machines can be had from Busy Bee but at up around $5K. Depending on your patience deals on used lathes come up now and then. But you also need to know what to look for on used machines to avoid broken gears, overly worn beds and a number of other possible issues. That's a lot to learn about in a hurry and avoid a machine full of issues. But if you know what to look for you can get used machines with lots of good life left in them. The best I can suggest for price is to start looking at the Craigslist or similar that apply to your area and watch ALL of the lathes, big and small, and gain a feel for the local pricing. Then jump on a machine which is in good shape and doesn't have any broken gear teeth.
Price wise
Pretty sure he's looking for power feeds and thread gearbox, not production equipment.
Suspect, given the location of the OP, that English is not his first language.
I'd say you are about on point, as far as the size he is like to be looking for.
I'll suggest that he looks pretty hard at the current suppliers at retail of metal working machinery, if only to familiarize himself with the features and options in the size range. Grizzly Tools, King, Busy Bee, even. Between those three, a fella will at least get an idea of what a lathe was or is selling for at retail, to see how the price offered compares.
You can accomplish a lot more on a minimal tooling budget with a lathe, than you ever will with a shoestring budget tooling up a milling machine!
Lots of great videos out there, almost as many good books, some really good websites, and lots of data available online through a search engine, that was never easy to find back when having a copy of Machinery's Handbook was consider a requirement.
If you have to buy just one book, buy Technology Of Machine Tools by Krar. Senior High School/College level metalwork shop text book. Awesome book. Buy an older copy, or a used copy from a used book place, new copies are running pretty close to a hundred bucks, because, who better to rape on book prices, than students! An older copy will have all the same good basic info, but will have less about CNC and such more modern technology, which is pretty handy to have if you are gonna make a living at it, but not so handy if all you really need is some instructions to follow using manual machinery.
Don't buy Machinery's Handbook unless you can buy a copy for under $20. Giant book of reference tables and data, not a how-to book. You can find it all on line, if you feel the need to look the stuff up.
Metal working machinery seems to be cheaper and more common in the East. Think it's due to it being our manufacturing base in the past. Atlas , Craftsman lathes have pot metal gears, made me suspicious of them. 
