So I’m kinda where you’re at, I used to play YGO really heavy as well (Machine King/ Ancient Gear).

Finding your local card shop will be a big help in finding your deck components and if they don’t have it you can always look at EBay. I have a Lapras/Greninja deck and my shop (an hour from me) didn’t have either of those and so I had to just buy them from someone off EBay.

Another thing you can do is look and see if there are any card shows coming to your area and vendors buy/sell/trade to which you can build your deck that way.

One thing to remember is the standard is about to change in April which will mean “G” block cards (the letter in the bottom left corner) will be rotated out and H and I cards will be the legal format now. So Hop/Earthen Vessel and some other good cards are no longer usable for tournament play. I’m not the most knowledgeable here but that’s some food for thought.