1:18 models, the majority have opening doors, boots and bonnets, with engine detail etc.
Size of the cars does effect the price but also these days a lot are limited numbers.
A few years ago diecast metal increased in price, hence model prices increased.
Collecting models will be expensive, when I started years ago the 1:18 Escorts where £20 in model shops, but now they start at £50 plus.
Otto models are resin and when launched are £50 with good detail, but no opening doors etc
Be prepared to spend a fortune, and a bit more