There are certainly people who do manage on conventional DMARDS (methotrexate included) for a great many years. There are a few on this forum who had this experience before changing to biologics, and with any hope, you will too.
I'm in Australia too - and the medicare guidelines, hoops you have to jump through, etc to get biologics seem so very convoluted and difficult it will never happen. Bear in mind that many people on this forum have more severe disease than average, or haven't yet found a treatment that works (that's why we are here), so there is probably an over-representation of biologics users (as well as the predominance of USA members - and their system is so very different from ours).
I didn't get any significant relief from MTX (maybe 10% in my hands, nothing in my feet, knees, hips, shoulders or spine, and nada in the way of fatigue relief). I had very sudden noticeable onset (from taking life at 100mph at age 36 to "I wonder if I'll need a wheelchair next week) in a 6 week period, had very little response to any other DMARDs, so I had a very strong vested interest and opinion on Biologics, given the results that are noted for PsA patients,
But what I did learn, from an Aus point of view, is that it is very possible your rheumy won't be in favour (mine wasn't - but is wasn't anything to do with cost, and everything to do with his fear of side-effects). And what I also learnt, is that you can most certainly ensure that the system does the right thing for you - as long as you can convince your rhuemy it is what you want, need, and are willing to take the risk on.
Certainly the biologics have a better record for preventing actual joint damage than MTX in all the double blind, blah blah... (feel free to come in and correct me Lamb). But if you have effective treatment with MTX, and you've got a rhuemy who is monitoring you for damage in a proactive way...... well I'd be very happy with that!
BTW Seenie - I don't actually know who wrote that guideline on the approach to PsA for Australian rhuematologists. Because I sure as heck haven't found one rheumatologist that practices it. Way back when I thought my life was ending (aka onset), I even emailed Nash (of Gladman and Nash), and he was prompt, compassionate and courteous in his response. But he told me that MTX was by far the best, and he wouldn't recommend any of the biologics, because of the risk. He has a family member with PsA who manages very well on MTX. He was so very compassionate, but in Australia, there is still that issue that the doctor is considered to have better decision making skills than the patient, and their focus is entirely keeping you alive - quality of life doesn't appear to be a strong contender.