As you've most probably figured out already space is at a premium with rc-ing 1/16 scale vehicles, therefore you need to use as small and compact hardware and electronics that you can find, I've attached some pictures of items that I've used in my vehicles.
If you use Aliexpress or banggood these are the best places to buy said items, you can find the same items on Ebay but you will pay a premium for them on there.
The esc's ( electronic speed controller ) which is basically the brain to running the vehicle can be bought for as little as a couple of quid from those sites and does the job well, if you want to add sound you can get a module that will give you generic sounds again for little money ( under a tenner ) but if you want to get more ambitious you can get a das mikro tbs mini which is programmable so you can add your own sounds and even lights etc but these are a bit more expensive. Here is a link to another members build on this site but be aware he is an electronics and radio wizard so be prepared to be astounded
( viewtopic.php?p=294301#p294301 )I would stay away from buying a complete vehicle as a donor as you will use very few parts from it and besides the sites that I mentioned above sell all the spare parts individually ( axles, motors etc ) so you can buy just what you need so unless you can pick up an whole vehicle really cheaply it's not worth it.
That should give you somewhere to start from, if you need any more help or info don't hesitate to ask
Cheers,Lee.
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