I don't think the WP25 comes with the laptop power supply. People buy the universal power supply so that they can use a WP40 in a smaller tank with a lower voltage. WP40 runs at 28W and peak at 40W.
The pump may not even start properly with lower voltage.
Why do you even need one with WP25 anyway? WP25 runs at 8W and peak at 25W.
If you really need one, they are like $12 on Amazon.