I’m not sure on pricing down under, but in the US it is common to see 10% off codes from retailers promoted on basically any holiday. Outside of that, just asking will very typically result in a retailer offering an equivalent discount any other time. So right from go, retail price is 10% greater than you could probably buy this new, assuming you find it in stock.
One aspect of pursuing modular is designing your instrument. Purchasing someone else’s system will probably result in choices you would not have selected for yourself. If I’m considering a system purchase that isn’t composed of exactly what I want, the seller is passing the resale of the unwanted portion onto me. They are also saving themselves the time and expense of making multiple individual sales, and the cost of shipping multiple sales if they don’t find a local buyer. Don’t discount the value this represents.
Buying from a retailer often gives you a local resource for dealing with warranty issues rather than shipping modules abroad to a manufacturer at your cost.
Add to that wear and tear / general depreciation, I typically approach used purchases with a ceiling of 70% retail for equipment in production. If a buyer is set on a higher figure the difference, for me, is often worth not inheriting someone else’s questionable usage history, no manufacture warranty, no retailer relationship, etc.
If this wasn’t my dream instrument I’d throw everything in a spreadsheet, total the retail cost for each part (this is complicated by parts that are no longer in production, but you can look at sales trends and make an educated guess at average value), then make an offer based on the figures. If everything is in very good condition I’d start at 65%. If you are looking to buy this on the sole reason that you are interested in modular, but don’t know where you want to start yet, and are considering this opportunity just because it presented itself, I’d really consider just walking away.
Unless you have specific goals in mind I wouldn’t recommend starting with anything smaller that 208hp for a case, then proceed slowly and really learn every module as you go. Modular is all about personal tastes, but I’d also in uninterested in most of the contents of that skiff. If I was looking for my first step into modular I don’t see myself putting together anything remotely like this.
I hope all that long wind helped at least a little bit.