What's in your medical kit(s)? And where do you buy supplies?
I have a kit in my range bag, one in my car and a real basic one that I have in my work backpack.
Some real basic things I have in the kit are gauze and elastic bandages. I also have Israeli (or similar) bandages in some as well as hemostatic gauze/pads in others. I have a chest seal and nasal airway in the range kit that came with a complete IFAK as well as the car kit. The range and car kits have basic stuff like bandaids and athletic tape. Those are the items that get used most often. Most kits have shears and nitrile gloves. The range kit and car kits have CAT tourniquets as well.
I've been shown the proper use of items like decompression needles and nasal airway, but I generally don't have those items in my kits. I thought about getting those to have them available for use by personnel trained to use those items, but haven't really yet.
Some of the sites that I've been buying medical supplies recently:
http://www.chinookmed.com/Lots of good stuff and easy to find what I wanted and at good prices. However, shipping can be pretty steep.
https://www.liveactionsafety.com/Pretty good prices and what I wanted. Decent shipping.
I have been avoiding Amazon for medical stuff because of concerns on quality. Some EMT/medic friends said many vendors are ok as long as the codes are correct, but many times I found that the prices weren't lower than other online vendors.
I've shopped at shopmedvet.com. They have TONS of stuff, but site seems tougher to navigate to find items, at least for me.
I have a kit from Dark Angel Medical. Others companies that I was referred to include ITS Tactical and North American Rescue.
One thing that I am wary of is rotating items that are left in my car kit since my car is parked in the hot sun where I work.