I think it just depends on where you're at. If you spend on the other component (crystals or money), you are more likely to be l ok w on the challenge gear piece which build up slowly over time.
I personally try not to buy challenge gear unless I really need it and focus my resources on the non challenge gear part when possible or other non challenge gear that I need if I am waiting on the challenge gear since it only takes about a week to get either 50 eye balls or 50 carbontis.
But we can probably all agree that 25k in ally points is a horrible deal for this piece.