AIBU to ask about the Father Christmas promise

[Tworoads]

My little boy is 5 years old. He is fascinated by all kinds of electronic gadgets, teaching himself how to move around a PC, load apps onto a mobile, work a Sat Nav etc. His favourite outing isn't Smyths or The Entertainer - it's Currys! He is also pouring over cars all the time, recognising manufacturers' logos and chatting about cars, cars, cars all the time.
So we come round to the letter to Father Christmas and he decides he wants a ride on Ford Ranger electric car WITH the touch screen radio built in. They are £400-£500!!!! I have found a different Ford electric car without the touch screen for £200 and might possibly stretch to that but it's not what he wants and the other one is out of the question.
He thinks Father Christmas is magical. He has no idea that he is asking for something so expensive - to him £500 might just as well be £5. He's a lovely little lad. Not spoilt but nevertheless, I have a problem.
How do I satisfy him? What would you do to make a little boy's dreams come true without bankrupting myself?

There is no other time of the year like it.

I use the wishlist idea year round, it's a great way to manage expectations and deal with requests in shops: "Do you want that on your wishlist?" was something I said a lot when mine were that age until they started asking for it to be on their wishlist themselves or in more recent years with smartphones, one of us would take pictures to go on the wishlist or if they wanted to show it to me if I wasn't with them.

Sometimes close to gift giving occasions, I'll ask them for the top 5 or so items which helps me narrow down what was a momentary want and what's on their mind a lot. This year, this somehow morphed to my DS2 picking out his 5 favourite cakes for his father and I pick from for his birthday...