The Matrix is a good buggy, safe choice. Also, this is still large scale but an FG Stadium Truck would be great as well, as I'm sure you're aware theres nothing like a gasser. Theyre big, but not as big as your grand national.

As for the pneumatic tires, I havnt seen any for 1/5 scale buy I do remember seeing some on a Pro1 grand national quarterscale once, but it was in person and I didnt get a chance to ask about them. But I'd assume they exist.

As for spending, hehe.... probably $500 a month on average, unless I get a new vehicle then its of course higher. My next toy might have to be a Pro1 sprint car.