Trace of Magic by Diana Pharaoh Francis (The Diamond City Magic Novels Book #1) is currently $1.99 in the US
https://store.kobobooks.com/en-us/ebook/trace-of-magic
http://www.amazon.com/dp/B00M4NSPRG
Urban Fantasy with romance.
Even the most powerful tracers can't track you if the magical trace you leave behind is too old. But I can track almost anything, even dead trace. That makes me a unicorn, the Tooth Fairy, the Easter Bunny, and the Loch Ness Monster all rolled into one. In a word, I am unique. A very special snowflake. And if anyone ever finds out, I'll be dead or a slave to one of the Tyet criminal factions.
Riley Hollis has quietly traced kidnapped children and quietly tipped the cops to their whereabouts one too many times. Now she's on the radar of Detective Clay Price, a cop in the pocket of a powerful magic Tyet faction. When he blackmails her into doing a dangerous trace for him, Riley will have to break every rule that keeps her safe. Or become a Tyet pawn in a deadly, magical war.