Just going to clarify some stuff. A crown is like a hat for your tooth. The original tooth is shaved down with a drill until it's a nub less then half the height and width of the original. Then a new tooth is made, put onto the nub amd cemented in place. The majority and visible portion of the crown is made of porcelain. The gold or zirconia is just the base inside, it's just a tiny cup that fits on top of the nub that the porcelain tooth is built on.

The base is not the expensive part of the tooth. The expensive part is the labor that comes from a technician sculpting a tooth that looks like the rest of your teeth and fits in your mouth. The rest of the expense is the labor your dentist puts in grinding down the original tooth, fitting the new one, and trimming it to size, getting the contact points right, etc... the actual base of the crown weather is gold or zircon is chump change compared to the rest of everything.

Now for the link you linked to. Those are implants, implants are not crowns. An implant involves removing the original tooth in its entirety, and drilling a titanium post into your jaw bone where the tooth used to be. Then a new tooth is built. So while a crown is like a hat, an implant is like a new head, installed on a new metal neck. Also see how those teeth are connected, non glossy, and not the least bit translucent? Those are temporary teeth. Placeholders made of some sort of plastic while the new teeth are still being made. Art takes time, temporaries are usually kept for a week to a month until the teeth are done.

To be honest I'm not sure if they even make zirconia posts, I'm fairly certain it's always titanium(i can find out though, I'll update when I do). Just the inside of the tooth is made from either zirconia or gold. If you pull a tooth the gum line is gonna be a little fucked since a bunch of tooth is missing, so I'm not sure what that picture is trying to show, it seems kinda shady to me.

Now as for the reason why people get zirconia crowns over gold. It's generally only done on the front row of teeth. Since those teeth are thin and slightly see through. Zirconia is white, while the gold alloy isn't. Those teeth look more natural with zirconia, but unless you're a dentist and see these things day in and day out most people won't even notice. There are drawbacks though. The bonding agent or cements that dentists use work better on gold alloy bases. You might have a zirconia cap pop off one day and have to get it recemented, this could happen to a gold alloy base too, but the chances are lower.

Source- have both types of crowns in my mouth (all look the same), son of a dental technician, do the accounting for a dental tech's small dental labratory.

Advice- get a gold alloy base crown.