At A$1,200, this looks ambitious rather than a clean buy for a Phase Linear 300 unless it’s been fully serviced and documented. Comparable working vintage Phase Linear power amps often trade more in the low-to-mid hundreds of AUD, with exceptional examples commanding more, so this asking price needs stronger proof of condition than “unknown.”
That said, the 300 has real appeal: lots of headroom, a muscular, classic American sound, and strong collectability among vintage-amp fans. If it’s genuinely clean inside, quiet, stable, and has recent recapping or protection-circuit work, it could be a satisfying long-term piece. At this price, though, I’d want service history, clear photos of the internals, and confirmation it has been bench-tested properly before paying up.
Independent perspective — not a price guarantee. Always verify condition, accessories and provenance before purchase.