Yes, I'd rather not spend £50 when I can spend £10 either, but if it does prove to be a more effective solution, I'd go with it.
If you can measure the current though, that would be awfully swell!
EDIT:
After Diago's lengthy disclaimer about using non-Aguilar power supplies, I got told this at the bottom of the email reply:
Electrical:
18V
20 mA
So there we have it Diago's voltage pump is supposed to provide 30 mA at 18V, so I think we have a winner!