Welcome to Librarium Online!
When you buy a squad of Vypers do you pay for upgrades like holo-field and cyrstal targeting matrix once or as many times as you have vypers?
Nevermind, found it :o, too bad.
And to answer the question: You can equip each Vyper individually, but of course you pay for 3 holo-fields if 3 Vypers have holo-field. However, as Black Katalyst said, that is often a waste. It's best to keep your Vypers cheap so just give them the weapon you want.
Warhammer Fantasy: Warriors of Chaos, High Elves
Warhammer 40k: Eldar, Space Marines, Orks