Cheapest US car rental with CDW/LDW for an European (German) under 24
Upvote:2
Some possible strategies include:
Check the figures from national. $800 for 28 days CDW seems excessive, but maybe that's how they are compensating for giving you a deal on driver age.
If you have auto-insurance at home, see if they will add worldwide coverage for rental cars to your policy. If they do it will be less than $800.
Get separate insurance to cover rental vehicles. There are plenty out there, and none are as expensive as $800.
Find a credit card that offers CDW as a perk if you rent the car with it. In North America there are plenty such cards, with fees much less than the cost of CDW.