Below are the prices across all the stores that I can think of that sell Hot Wheels, with the various deals you can apply, the ultimate being $1.70 per unit at the Warehouse. Note this deal doesn't work instore as they don't stack deals.
| Store | Price Per Unit | Units Required | Notes |
|---|---|---|---|
| Toy World | $3.99 | 1 | |
| Whitcoulls | $3.99 | 1 | |
| Countdown | $3.20 | 1 | |
| K-Mart | $3.00 | 1 | |
| Farmers | $2.62 | 2 | Buy One Get One Half Price Deal |
| The Warehouse (Instore) | $2.25 | 2 | Buy One Get One Half Price Deal |
| The Warehouse (online) | $1.88 | 4 | Buy One Get One Half Price Deal, stacked with Buy 4 for $10, Free Delivery Code |
| The Warehouse (online) | $1.70 | 28 | Buy One Get One Half Price Deal, stacked with Buy 4 for $10, Spend $50 Get $5 Market Club, Free Delivery Code |
I couldn't get a clear answer from the staff but it sounds like exchanges would be possible, so if you weren't happy with the selection they send you could swap with other cars instore - but best to check with the online chat first if you intend to do this.