Lasers are always a single colour, and they will always work worst against a balloon of the same colour because it reflects that colour of light the best.
The only way to make up for it is with a really powerful laser My recommendation is a nice powerful blu-ray at 100mW+. Not only are they extremely cool for so many reasons, but violet is an unusual balloon colour, and blu-rays burn really well!
Since so many people are selling, you could probably just make a thread like:
"I want the most powerful blu-ray possible, what's the prices?" and people will come to you Make it in the Buy, Sell, Trade section of the forum of course