True!! At least in part;
One , significant benefit, if you are building in Australia - As the builder, you decide a whole host of matters associated with the aircraft. The purchaser, of the completed second hand aircraft, gets to live with these decisions. The purchaser of a completed kit is not much diffrent to the purchaser of a factory built aircraft ie you can not change very much.
As for purchase cost - much will depend on quality of build, engine, prop and avionics choices, maintenance record, flight hours, (for Rotax) calendar age, etc and of course the reputation of the aircraft. A good one will cost you a lot more than half the build cost, possibly for a very popular one, more than the build cost. Build cost is usually materials only - the hours & years of building rarely get recognised in the sale.