Any old spoon will do; regardless, the bottom will get caked with soot because of the candle. A lighter or oil lamp might solve that issue.

• Nostalgic Impressions has a brass spoon with a wooden handle (to protect your fingers).
• LetterSeals.com has one that appears to have a slightly smaller bowl.
• I found this on Amazon and, while I lust after it, it is out of stock (in the U.S., your local Amazon might have it).
• This one is better priced than some of the others but doesn't have a finger-protector or a spout and shipping makes it more expensive.
• This set up looks absolutely fantastic but also overkill—of course, you could likely adapt a liquid incense heater for the same purpose.

Found these with a google search of "wax spoon", but I've searched for similar before, so my Google's been pretty well trained!

Let us know what you choose!