Thrift stores might also be an option for black candles, some places will stock them outside of halloween.
Djinn tend to have a field day with the emotional spectrum, especially any arrogance in their summoners. Ensure you take wise precautions to guard your mind and self, and don't ever underestimate a spirit you summon. Just because you don't feel in danger, doesn't mean that you are infallible.
Be wise, safe, and learn from the experiance above all.