[woodcote]

In the UK, they are common. Jadlam Toys & Models sell the individual cars and all the sets.

In terms of US retailers, Hornby USA sell individual cars For $14.99 each - which works out the same as we pay in the UK: https://www.scalextric.com/us-en/shop/by.../cars.html

American retailers that sell Scalextric should also sell them, but be aware many will also sell the old-style Micro sets. I found this new 2019/2020 set for $35 at LEB Hobbies - two cars plus the track we use (although I bump it up to 12 volts):  https://www.lebhobbies.com/g1151t-micro-...Path=4_608