Primers and powders are the main cod-lock in reloading right now. In that order.
If you can find 4 cent primers, jump on it. That's about half of what you'll find pistol and rifle primers for.
You can probably find wads pretty easily. I haven't really looked in a while because I bought a bunch probably 6 or 7 years ago that I'm still using up so I'd be a little surprised if you wouldn't be able to find any.
I second nitesites recommendation of trying to use remington smooth shells. They can be reloaded a bunch of times. And work well in various guns due to being smooth. And the figure 8 wads are what the factory uses, so there's no issues with fitment.
Though, I have used a lot of other style wads too. Winchester and federal.
Another all time favorite for buckshot are the hornady versalite wads. Those are my #1 pick for patterning buckshot. They tend to do better for me out of virtually all my guns for buck. Don't know what it is about them that jives so well for buckshot? But, they do well.
What brand of hulls are you going to be reloading? I can look at my recipes and see which wads and stuff that I'm using to maybe help narrow down your search
Hint: if you're mainly going to be shooting a particular brand, if you are wanting to mimick factory loads, it's easiest to stay with the same brands. And most have generic options too. Claybuster and Downrange to name two and probably others as well. So, don't get hung up on the name brand. A figure 8 wad will be close enough no matter the name on the bag.
Rem= figure 8 wads
Winchester= WAA12L wads
Federal-= 12SO for light and 12S3 for heavier payload wads
I haven't loaded any imported shells like fiocchi and centurion and such, so I don't know what wads may work best in any of them.