Advice please

[Nullin]

What item would work out to be the best bang for the buck that equals the Expert Attack Drones, since I don't buy gold?

[Товарищ]

What do you mean?

I'm guessing these two spreadsheets can help you out somewhat...
http://www.funzio.com/forum/showthread.php?40885
Especially the first one with the tabs "Strongest Cash and Valor Attack Units" and "Strongest Cash and Valor Defense Units".