Depends what you want to do. Here’s some criteria:
What scale do you want?
What type of car do you want?
What do you want to do with that car?
Can you use it in your area?
What would make this car stand out from your others?
My personal example is my Losi rock crawler. I got it thinking it would be nice to have a crawler. 2 crawlers and a slash later, I am selling it because it didn’t do what I wanted to do. Now I want a new car:
A 1/10 scale
A buggy
I want it to perform well at the track since the slash isn’t that great for it.
Yes, when I’m not at the track, it can go on trails and bomb down the street.
I want something fast that performs. I have 3 rock crawlers, they’re slow, and I don’t need a fourth one. The slash just doesn’t get the performance I need at a track.
That’s an example of using my criteria. My local track is selling a lightly used Losi buggy for 150. I have the electronics now, and am going to sell them the crawler for the same-ish price. Maybe even trade. Just because you have 800 doesn’t mean you need an 800 car.
hope you find this useful! Happy shopping!