To be able to obtain the Destreza Prime you have different ways at your disposal, being the first and most expensive one, to buy the Limbo Prime Access, which includes both the Destreza Prime and the Pyrana Prime. If you choose this option you also get unique accessories included in this pack.
Trading with other Tenno is your second option to obtain the different parts which compose the Destreza Prime. To be able to choose this option you will need something the other Tenno wants, usually Platinum. What it may cost you depends entirely on your trading skills.
And finally, you can also obtain the Destreza Prime through the Relics which contain its parts. To do that you need to obtain the Relics, open them in the Void Fissure missions and pray to have enough luck to obtain what you need.