Used electronics can be hit and miss, especially used motors and batteries... no telling if they were ever over heated, etc...How much life is left is only a guess.
Buying a used Losi or TEKNO SCT makes a lot of sense to save cash, they are both built like tanks, I still race an original release SCT410.1 that is 6+ years old and still have 90% of the original parts on it!
What I like most about TEKNO is that they offer a 50% lifetime warranty on any broken/worn parts you mail into them. That said, TEKNO tends to wear longer than most other brands, and Losi is known to get fairly sloppy links so don't be too alarmed with a used Losi if it feels worn out, just make sure the out drives are not chewed up and no flat spots on the pins of the dog bones and then you'll probably be in good shape for a used rig.
My truck has gone through 3 sets of motor/ESC combos, and about a dozen battery packs over the years... and 3 sets of servo gears. It has a Savox 1258 servo and the gears start to wear every couple of years and need replacement. You can feel the slop in the main spline when it's time to replace a gear set. Savox is pretty pricey on replacement gear sets for around $25/set. If I would do it over again, I would go with the
Eco Power WP120T servo which offers replacement gear sets for only $13. You can also cut corners with a cheaper servo like the
JX CLS-5830HV servo but they don't offer replacement gear sets which makes the servo disposable after a couple of years.
For a modest basher, I would consider the
Radiolink RC4G system, you get a lot of bang for the buck!
When it comes to ESC's I have grown to trust HobbyWing, I would consider the
EZRun Max10
For a motor, I would consider running the
HobbyStar 550-3500KV motor on 3S. Lower KV and higher voltage will improve efficiency and run time
I would consider this
3S-30C-5.2Ah pack for a reasonable balance between price and performance.
A wide range of
Pinion Gears (15T-19T) is good to have as well.
Any B6 series charger will do if you want to save some cash something like the
Imax B6AC 50W
Only issue with charging 3S is that 50W / 12.6V = 4A charge rate so it will take just over an hour to charge the pack with the charger I referenced.
If you want to reduce charge times, then consider getting a higher C rated battery (preferably 100C) and a more powerful charger 150W+ to get charge times around 30 min.
Some tools here worth adding to your shopping cart too:
Tools for the Pit Table
Some more threads that might help you get started:
What gearing for upgraded electronics?
How to setup steering
Vehicle Setup Adjustment and Build Tips
Vehicle Setup Guide
Good Luck!