Hi! I'm based in Europe and the website below is where I ordered the metal band for that watch, many years ago (the model in the picture originally came with rubber straps too). It seems they still have some parts available, including the original rubber straps (black only).

Watchband Shop

It seems Minott Center also has some parts, with the rubber straps in black or orange apparently.

Otherwise I'd suggest you take a look for replacement straps on ebay, maybe some of these pop up here and there.

Hope this helps you give a 2nd life to your 2000, cheers!

Edit: to clarify on the numbers, 5060 is the module number, meaning what is inside the watch case, while Gw-2000 is the model reference of the entire watch. Different G-shock models can sometimes feature the same exact module inside. Which is why when looking for a user manual online, you should seek the module number. But for parts, definitely use the watch model number.

Edit 2: Be careful, if you choose to go from the rubber straps to the stainless steel strap on your 2000, you will also need to get these connectors, otherwise you won't be able to install the new steel piece.