Hey,
I'd recommend Looking at these 2 threads on the official Infinity forums. I really found them useful when expanding on the special offer army deal back in March / April.
http://www.infinitythegame.com/forum/showthread.php?tid=4324 http://www.infinitythegame.com/forum/showthread.php?tid=4367 Just as a starting point, the Ariadna army deal consisted of:
Ariadna Starter Box
Equipe Mirage-5
Tankhunter with Autocannon
Zouave Sniper
If I were you I wouldn't just stick to the Kazak faction. Ariadna has some great models and themes but they really work best when taken as a whole. They have some of the best scouts/skirmishers in the game and some good heavy support choices.
If you decide on an individual aspect e.g.: Kazak (Russian) or Merovingian (French), you're really limiting yourself. For example the Ariadna 112 is a great unit but is French in theme, likewise the Paratroopers.
What about taking other units and painting them up in a single unifying colour scheme like the Kazak colours?
If you're working off a budget and just getting started I'd recommend picking up the following:
Ariadna Starter Box
Tankhunter with Autocannon (This guy is as good, if not better, than the big T.A.G.s / Robots that other factions have & is a must)
Tankhunter blister:
these 2nd Veteran Kazak:
these Zouave Sniper or Zouave Heavy Machine Gun
Paratroopers
Chasseurs
SAS Doctors and Engineers are also useful.
Hope this helps!