Remus Lupin

The purest answer to the question you explicitly asked is: yes, I am capable of brewing Felix Felicis. I have successfully done so once in my life, though not for my own use.

As to the question you meant — whether it would be a logical means of last resort for the Order — the answer to that is, almost certainly not, for both esoteric and exoteric reasons. It is a fiendishly difficult potion requiring precision and exactitude to brew correctly and nonlethally, including three separate phases of requiring direct and personal attention from the brewer for an uninterrupted span of twenty-eight hours at fifteen-minute intervals, and from inception to completion takes several months. Its ingredients are not only dreadfully expensive — to prepare a single dose would likely cost hundreds or thousands of galleons; I have not checked the cost of ingredients recently enough to provide a more accurate assessment — but many of them are not obtainable legitimately save through the professional channels no longer open to me. Black-market sources not only drive up the price, but cannot guarantee the quality — and a single ingredient not of proper grade and known potency again will turn the effect from luck to lethality.

Beyond that, however, relying on Felix Felicis is a poor choice for so many reasons. The 'luck' it creates is indeterminate and indiscriminate — and it only affects the drinker, not others the drinker prizes. Should you drink a phial of Felix when in danger for your life, it might very well save you — at the cost of your daughter, or your colleagues, or the destruction of the Order. One need only look at Selwyn's plotting, and the outcome thereof: he and his collaborators succeeded in their immediate plan, but once the effects of the Felix Felicis wore off, Selwyn lost status, wife, and life afterward, and his children nearly lost their lives as well.

Too, there is a limit to how often one might rely upon it. It is commonly put about that overuse on Felix will lead one to ruin because it turns one dangerously arrogant and overconfident, or that one ought not take it too often because it concentrates all your allotted luck for a period of time into a single day and leaves you with none left for a time, but the prohibition is more grounded in reality than that: the potion lingers in one's system for an inordinate amount of time after dosage. Years, or decades. Taking another dose before one has finished interacts poorly with the potion that is already present in your system, and the results are invariably a disaster, for you and for the people around you. More: the length of time it takes for each person's body to process the byproducts of the potion is individual, and there is no way to know when you are clear to take another dose.

I have another half-dozen reasons why one should use the potion for any reason other than amusement, should you need them.