This is easy to get right at the start of career.
- Start new career game
- Go to your office PC and open Shop
- Go to Graphics Cards
and scroll down to DFL Radeon R9 290 GR8TOR
- Add it to cart and go to View cart
- Increase the number of units to 10 and click on Buy Now
(cart total of $3,260)
Achievement should unlock right away when you click on Buy Now. I suggest starting a new career game after this and overwriting it. No point in starting it with a purchase of 10 GPUs.
This can be paired with the Skip 7 days achievement in the same career game.