Hey there! I'm happy to hear that you're excited to playtest the CoA Alpha.
There are several ways of acquiring CoA Alpha access without buying it using DP.
The primary ways being:
Buying from another player using Gold (possibility of striking a better deal than Auction House).
Buying directly from the Auction House using gold.
Signing up to our Newsletter where we occasionally send out access to randomly selected subscribers.
With the merge of Mal'ganis and the arrival of TBC to Al'ar there has never been a better time to get out there and farm some gold, it should only take a couple of days to be able to purchase access with gold! And you will still financially support the development of Conquest of Azeroth even while buying it using Gold as another user will have had to buy it with DP before selling it!