We too, see many combined classes in the same heat.
As you mentioned, it's not a cheap sport to participate in. Even in our vintage H class, our annual expenses are between 10 and 12K. Thats if we don't blow the motor up. We don't pay any rent for the shop we keep her in thanks to a generous friend.
Amazing, it's the same shop where she was built in 1962
We only attend 6 or 7 events. There is zero prize money in our class, just an entry fee.
We do it for the connection and heritage. A little speed factor helps too.
Good pictures from your cell phone. Thanks!