Short answer: your car is worth whatever a Perth buyer will pay; longer answer: start by finding comparable makes, models, years and kilometres in WA and note their asking prices.
Private sale usually nets more than a trade‑in (often 10–20% difference), but you’ll do the photos, the chats, and the awkward driveway goodbyes.
If your model is still sold new, its current RRP sets the ceiling; used values sit below that, sliding with age, kilometres and how lovingly it’s been serviced.
Condition, full service history, options, tyres, and even colour swing values; high kms or accident records tug prices down faster than a Fremantle Doctor.
Use Tradingpost to benchmark live listings, get a couple of dealer appraisals for trade‑in reality, and average the numbers for a sensible figure.
Then buffer a little for negotiation and on‑road costs; if it sells in a day, you were too cheap, and if it lingers, the market is politely disagreeing.