The offer actually says 800 points for spending $50, but you are allowed to complete the offer twice. You can also do this with a single $100 gift card and don’t have to bother with two $50 purchases. Expires 8/20/16.
There are quite a few gift card exchanges paying out 88% on Best Buy gift cards, so you come out with a small profit as long as you value Plenti points over 0.75 cents each.
This is obviously a small play due to the $100 limit, but hopefully this helps someone with a minimum spend requirement.