If you decide on using 30 minute road flares instead of/or in conjunction with the electronic flares then you might consider making your own road flare container or buy one from safety or auto parts store.
You would be surprised on how many people DO NOT have any form of emergency road signals in their vehicle.
Using some thin wall 4 inch PVC Pipe you can create a suitable container that allows you to store 9 flares inside. End cap, scrap pipe, threaded female adapter and a male threaded cap and an application of a high visibility plastic paint (Yellow or Orange recommended).
Some excellent options are to apply labels and DOT Reflective Tape (not shown) as well as one of the new Large ICE Stickers. Have those work gloves nearby as well - molten burning flares can wreak havoc on uniform wool pants or your bare hands.....trust us on that one.
This will protect the flares from damage due to shifting loads in your vehicle and you won't have to smell the obnoxious fumes from the chemicals in the flares.
A rope handle tied onto the tube might make it easier to carry around - commercial versions have a handle built in.
You can get a commercially made one for $11 online at Gall's - http://www.galls.com/style.html?assort=general_catalog&style=HS208&cat=3145
Learn how to use these flares BEFORE the need arises because in an emergency you will not be able to read the fine print instruction on the side of the flare - learn how to fold over the wire stands that holds them in the air. Don't get the spike tip flares - you'll have problems either spiking yourself or making the mistake of punching them into the pavement when lit and burn yourself or your clothing.
Just don't forget to get the flares!