If I'm reading this right, even with only a short lead-in time you can still use the trick with a cheap wand providing the spells to produce a shower of, say, 50 magic missiles at the start of combat. Or with a different wand/spell to have a dozen dispel magics ready for counterspelling as a free action.

In fact, the wand version lets a couple of level-1 noncasters pull it off if they don't have to pay for the Spellblades.