Sorry, but what makes you think he's got enough of a case that might make the police feel they want to get involved, let alone get a search warrant?!?!
How would they even know that the kit (sizes & finish) is in fact, as you say, ultra rare? (I'm a drummer, and I honestly have no idea just how rare it is...)
The police probably have no idea how rare a kit like this is...they would have to take the word of the person reporting the theft. There are a few things working FOR getting a search warrant:
1. The rarity of the specs of the kit. The sizes are uncommon. The wrap isn't one of the most popular ones--you see more broken glass, marine pearls, and wood finishes out there. Also, the satin chrome hardware is probably the most uncommon part of the kit...it's a specialty option offered that you hardly see on DWs. Those 3 elements together make this seem like much more than a mere coincidence. If it were a broken glass glitter kit in a 10/12/14/16/22 configuration with chrome hardware, then it would be a different story...
2. Same geographic location.
3. The timeframe. People who steal stuff typically try to get rid of the evidence quickly, before police reports have time to be filed (that's why most used music gear shops do a 30 day "police hold" before putting items out on the floor). Also, Davelarue could send this thread to the police as evidence of when his kit was stolen and compare that to the date/time the auction started. Hopefully he filed a police report too. THAT is key.
The least the O.P. can do is try. If the police think that there's no good reason to get a search warrant to simply check out the serial numbers, then davelarue has done all that he can. If they do, and it turns out to NOT be his kit, then it's simply a very minor inconvenience, no damage done.
I agree with checking with DW about the commonality of this kit. If the only 13/18/24 they ever made in black ice finish with satin chrome hardware was sold to him, then this is for sure that kit. If they made 6 identical kits, with one in Florida, 2 in California, 1 in Canada, 1 in New Zealand, and 1 in Boston, that would still present a solid case. Or, simply the verification from DW that they made more, but that this kit is not-so-common anyways, might also be used to show the police that this is a probability, not just a possibility...