Good players for Extreme who are mostly easy to buy are
Rustu (Tur)
Van Der Saar (Hol)
Edilson (Bra)
West (Nig)
Mostovoi (Rus)
Babangida (Nig)
Toefting (Den)
Denilson (Bra)
Djorkaeff (Fra)
Rebrov (Ukr)
Mpenza (Bel)
Olisadebe (Pol)
Sand (Den)
And Agahowa is known to be good but I haven't tried him yet.
And you can also be cheeky and buy Classics if you want.
The best dealing I did was to buy Maradona for free and sell him to Barcelona for 12,000 points.
I bought Rivaldo and Nedved after that I think.
Eventually when you can, go for Shevchenko because he is the KING!
(Guess who I voted for...)