Coin Collectors

I’m looking to start my own coin collection, and I figured a decent place to start would be to buy the U.S. Government Proof Sets that are issued every year. From my understanding, these are just a few coins (I’ve seen 4-5) that are packaged nicely in what looks to be an air tight container, and I believe you receive some sort of certificate along with the coins. I’ve done a bit of browsing online and noticed that they can come in some different type of cases, so I was wondering if anyone could explain to me the differences in the cases, and the differences in the types of coins that are issued every year (if there are any). I’m just looking to collect the standard ones issued every year. The ones I have in mind are the ones that come in cases that are green, purple, blue, etc.

I was wondering if any of you had any recommendations for reliable websites that sell these sets from EVERY year they were issued. Obviously I prefer websites that are the cheapest when it comes to the actual set, as well as shipping, but I also don’t want to order from a shady website. I understand if members are not allowed to promote for websites in their posts, and if that is the case, then could someone just PM me a suggestion?

Thanks for all your help!

EDIT: I also want to note that I want to buy the original ones that the government sold, not remakes or something like that. I would also prefer them to be new sets that are in good condition with minimum wear and tear.