You can modify spell completion items with metamagic when you are creating it. Quicken does affect an spell completion to a swift action. Applying a metamagic feat to any spell completion item will raise both the caster level and the spell level of an Item.
Quicken cannot be applied to a potion and are limited to 0th level spells for wands. Why? Quicken adds 4 spell level to the effective level. Potions can only hold (normal, that is) 3rd level spells and Wands can only hold 4th level spells.
Lets compare a Wand of Ray of Frost vs a Wand of Quicken Ray of Frost build cost for 3.5.
Wand of Ray of Frost = 1 x (1/2) x 750 = 375 gp plus 15 xp
Wand of Quicken Ray of Frost = 7 x 4 x 750 gp = 21,000 gp plus 840 xp
The Wand of Quicken Ray of Frost is 56 times the gp cost of its non quicken relative.
If a PC really wants to invest that much more gold to gain a swift action that does 1d3 frost damage with a touch attack, why not allow that? An extra 1d3 damage a round is not going to break the game.
Just remember to enforce the increase in SPELL LEVEL and CASTER LEVEL.