I bought one,not over keen on the Fenix side switch so exposed as it is on other Fenix lights I own.Must admit gone back to using my Eagtac D25A clicky.
Talking in £,s so no doubt a UK village resident.Great vendors on the site such as Flashaholics who offer a nice discount but suggest you use your head a bit and think what is around you in bricks and mortar stores so to speak.Maplins.Arco.Machine Mart, for example all sell lights and with Arco...
I would also return your bad lights to Costco.I after a heads up from a customer bought a pack of 5 penlights a year or so back and they have proved to be a very good purchase and what made the deal super sweet they were badged as Snap On.
I am a real convert to the D25 series and I prefer them to Fenix.The strobe function never causes me an issue and I fully endorse Tac Gunners findings.