cnc lathe/mill

Hi,
I am about to get a bonus at work, and this is my chance to get a
lathe or mill and I want to convert it to cnc use.
I like to play around with small turbine engines, and I want to
start making my own instead of buying parts, so I need a lathe and
mill, but right now I can only get one of them. Most of the parts
are symetrics, so the lathe will probably be the better choice
although with a mill I can machine all kinds of stuff. I found tons
of information on retrofitting a mill for cnc use, but almost
nothing with a lathe, so I was hoping you all could help me out a
little.
First lets talk about lathes.
Can anyone give me some information on a good lathe with a size
around 9"x20"
Here are three I found that are about the size I need and in my
price range:

Grizzly G4000
http://www.grizzly.com/products/item.aspxitemnumber=G4000

JET 321373 BD-920N BENCH LATHE http://cgi.ebay.com/ws/eBayISAPI.dll?
ViewItem&item=6003249800&rd=1&sspagename=STRK%3AMEWA%3AIT&rd=1
or
Lathemaster 9x30" lathe
http://www.lathemaster.com/LATHEMASTER9x30Lathe.htm

Can anyone give me an idea on which one would be better for
converting to cnc? Also what size stepper motors would I need for a
lathe of this size?

Mill
If I go with a mill, I was thinking about:

RongFu31
or
Lathemaster mill
http://www.lathemaster.com/HEAVYDUTYMILLINGMACHINE%207045FG.htm

Does anyone have any suggestions on what mill they would get, or
know of any other brands about this size. The taig mill is too
small, and I don't want a huge knee mill either, so these are in the
size range I want.

Also about ballscrew and stepper motors
has anyone ever bought ball screws from this site
http://www.homeshopcnc.com/ , and are these stepper motors any good
for the size I would need. I'm guessing around 600-1000 oz/in
motors. I know ground ball screws are much better, but i dont got
that type of money. any suggestions on this topic would be helpful.

Sorry for all the questions, but I'm trying to figure out which
route to go, and then what machine to get after I decide mill or
lathe.
-Jason