From a quick look at Basil, you're going to have to get very lucky to find a 95 MATK Evil Wings on Bera for 30 mil... considering 93 MATK EWs are at 30 mil already. But I agree, you probably want a strong one. I don't know enough about skipping until Kage to tell you anything about that.
As for the rest... Well, a Black Gaia's seems like overkill. It'd be better to wear one of the Icarus Capes, unless you're planning on scrolling it with INT. Millions for a few points of defense doesn't seem the best use of money.
Are you talking about for the actual job advancement itself? Because I've seen several vids on YouTube. It seems disturbingly easy if you get Holy Arrow, rather hard if you just have Magic Claw, but it depends on the person, too. One of the vids was a pure party cleric Magic Claw-ing Grendel... She died four times. o_O; But no matter what, you'll get through it eventually. It's such a small portion of your time in Maple.