(e.g. $27 000)

Ok so they're winning $27, but I thought it was filmed in America, not Australia. Shouldn't that be $27 911?

/s, obviously.

But more seriously, yeah a space is brilliant. But you shouldn't use U+0020, the space you get when you press spacebar. It's awkwardly wide for this purpose, and more importantly it can break the number over two lines if it happens to line up that way.

The best alternative is U+202F, which is both narrower and non-breaking. Wikipedia claims that the official SI recommended character for thousands separation is U+2009, the thin but breaking space, but I read their source and did not see this supported. It seemed to just say space, without specifying which type of space. There is of course also U+00A0, the no-break normal-width space. Any of these would be better than U+0020.

The problem is them being difficult to type, which is probably why most people tend towards the comma instead. It's automatically non-breaking and doesn't have the awkward wideness of U+0020.

Incidentally, SI specifically allows for either the comma or the point to be used as the decimal separator. As long as the thousands separator is a space, this can introduce no ambiguity.