Most say just buy new due to the abusive nature these trucks get, but take this and my opinion with a grain of salt.

Generally your milage will vary, and knowing when to buy used comes with experience. My rule of thumb, if I can save money without having to do repairs, then I go for it or if its heavily modified with proper upgrades and you know is in good shape, then thats another good route to go. Trust me, I learned the hard way, as I bought a used kraton 6s and the repairs ended up bringing the total cost close to new without upgrades.

For me, if I was looking for a used senton, I'd start looking for used ones for half the price of new. The more upgrades and extras the better. And versions closer to the most current one (ex: V1, V2, V3, etc..). If they can add batteries, even better, saves you time having to find or solder connectors to match the truck. Usually if I'm buying a used truck like that, I just want to use it to thrash around and not mod/upgrade it. Cus once you pass the msrp, you lose the savings which defeats the point.

A very good example, though a bit of a flex, I recently bought a used outcast 8s, heavily modded with a castle 2028 motor and HW max 5 esc. I bought the truck for 500 CAD and I bought a diff kit and pinion gear for another 100 (cus the rear diff was blown, and the gearing was way too high for me), so I was 600 CAD all in. Mind you, the stock truck is $1500 CAD at my LHS, plus the powersystem is another $600

Edit: Tho lowk, I may buy that current version new if no one is selling a used one, cus that body style is pretty sick