Every price is 50% off while your Career (Wardog) level is below 9. Sources split on whether level 9 itself is still discounted, so plan as if it ends the moment you reach 9. Once it ends, it is gone for good.
The window is short. Spend it on durable gear you will use all season, not consumables: Level 1 Armor + Helmet ($17,500 [S1] full, $8,750 [S1] discounted) and a good optic, since attachments carry across every weapon and class.
It is not confirmed whether the discount covers one-time blueprint fees or only per-life vendor prices. Check a blueprint's listed price before you count on the saving.