It is very difficult to figure out where to get your items at first, especially when you are looking to do a lot of items.
The main thing I highly recommend when getting started is to focus on 1 main product with 1 main material. There are so many variables when it comes to physical items, that you really should not go after every idea, or you'll spend a lot of time sourcing material all over the place and then spend a lot of money as well.
Also, I highly recommend you step back and do some research on the market for printed cards and bookmarks. Unless you sell a high quality, custom leather or ceramic bookmark that is stamped and foiled, and costs $20 USD or more, you'll be competing with people who can do $1 bookmarks.
Same goes for Cards. A Physical Card that is simple, usually goes for $5. So if you had craft, make, package, and ship each one individually, you'll be spending at least 10 minutes on each just to make a couple dollars.
So, unless you can mass product cheap items, I highly recommend going after a bit more of a high-quality, custom, or very elaborate market, to make it worth your time for physical items.
The other thing is, definitely start with 1 product. Bookmarks are extremely cheapand people expect to spend $2 on them, so I don't think they're going to be a slam dunk right off the bat.
Also, yes, unless you go to large printers who mass produce these items, the other option is to hand-make them yourself with your own machinery, which is very expensive.
So start off with something that is feasible and realistic for you, and you don't have to spend a lot of money getting up and running.
Gold Foil is also extremely expensive. My husband designs wine labels for larger wine companies, and the printing in the US is extremely expensive. Only in China is where the prices are affordable enough. Like you said, the machinery is expensive, and the prints only go for $20 each. So you need to sell at least 50 prints in order to get your money back. Definitely not impossible, but it's a lot of work.
Also, a lot of shops on Etsy are hobbyists. They are not business people, so they are probably losing a lot of money. And they're burnt out and frustated, because instead of trying to make money, they want to be artists, but they lose a ton of money.
So, I highly recommend that you focus on 1 item, 1 physical product. Make sure it is the easiest thing you can possibly think of. Make sure it will cost you almost no money. And make sure you can actually make money selling it. My husband and I have lost a ton of money doing physical items in the past because we had no clue what we were doing. And so it's good to test things out, and try things out, but you want to make sure you can:
1) Make money immediately
2) Spend almost no money
3) Get your idea to the Etsy market ASAP
4) Take it one step at a time
5) Refine your idea along the way
6) Be willing to dump your idea ASAP if it is not working out
I hope this helps! It's difficult, and it is almost like starting a whole new business from scratch all over again.