This for me, is a far more realistic way of looking at points "worth". Citiflyers way works for Citiflyer and probably many others, but without points or points and pay, a business class fare is indeed that value regardless of whether Citiflyer or others would pay it. So it comes down to a fairly simple (non-monetary) equation of "would I prefer to fly 6 hours or so in cramped economy" or "would I prefer to burn some points I effectively got for nicks and travel in the comfort of business class AND perhaps save a few bucks into the bargain".
I've looked at similar rewards (mine was BNE-BME) and having experienced the DJ business product (though not to PER) and experienced the BNE-PER sector in Y.......there ain't no question in my mind as to whether it's worth it. Remember, the SYD-OOL sector just may be business as well!
I am not sure if I fully got your point, but what seems to be really important to me is that for calculating the value of a point, one should use one's own subjective value of a flight. The market price does not reflect a realistic value of a flight when it comes to spending your points.
Three examples:
1. Business class flights LHR-AUH-BNE-AUH-LHR are waaay cheaper than Business class flights BNE-AUH-LHR-AUH-BNE, but obviously we are talking about the very same flights here. So why should these, from my subjective perspective arbitrary market prices reflect my personal value of such a flight (and give me an indication on what I should spend my points on, if I want to spend them wisely)?
2. For me it makes a difference if I travel to PER on holiday or if I have an important business meeting and know I will not get enough sleep the night before. In the latter case, a seat in Business class might well be of a higher value for me because it might lead to better business. Obviously, market prices will not change due to my personal situation. Nevertheless, my personal situation might well have an impact on how much I value a flight.
3. Bananas are ridiculously expensive in Brisbane (AUD15/kg or so). I love bananas, but if I could spend my points on bananas I would not calculate the value of my points on the basis of AUD15/kg. Because I am not willing to pay more than AUD5/kg. Valuing points on the basis of the current banana market price would lead me into buying bananas at a price that I do not buy bananas, i.e. would lead me into wasting my points. (And as I love bananas, I really hope prices will go down soon.)
In the case above, I would proceed as follows: normal circumstances given, i.e. no special Business meeting and enough sleep, I would be willing to pay up to about AUD600 (return) for flying to PER in Business instead of Economy and I would consider any amount above a waste of (my) money. This is my subjective valuation of a better seat, better food and more fun on the flight. In terms of points, this would mean (for the points + cash option) a value of about 4c per point, which is excellent. So if I can buy a point for 1c (as in the original question with the credit card), I would definitely use my points here.
If I did not want to fly to PER, or could not earn the points I would need for this flight, or if I valued a Business class flight to PER much lower, the number "4c/point" would be an entirely futile, abstract speculation (and might lead to inappropriate decisions). And this is why I suggest valuing points on the basis of your subjective situation.
Now back to the bananas to emphasize my point. Let's assume I could buy 10kg of bananas for 3000 points. If I use the current market price of bananas, my points would be worth 5c/point. So should I buy bananas instead of flying to PER in Business because my points would be worth 5c instead of 4c as in the PER example? Obviously not because valuing a point at 5c would imply that I would be willing to pay AUD15/kg. So my point comes down to this: If you wouldn't buy a business clas upgrade to PER for AUD600 in the supermarket (as I would not pay AUD15/kg of bananas in the supermarket), you should not value your points at 4c. And depending on what your subjective answer to this questions is, you would pay for these bloody credit card points we started with, or you wouldn't.