Possible Clues:

• My twice-used letter opener?
• Twice as expensive? Oh, my!
• Too bad that it's twice as expensive!
• Too bad to be worth only a 10 across of bucks, by the sound of it
• Too bad it's only worth a couple of bucks, by the sound of it! (4,4)
• Regrettably, it's twice as expensive
• What a shame it's twice as expensive!
• What a pity it is twice as costly
• My double!
• Duplicating expensive? Too bad!