Search youtube for the models you are interested in. There are bound to be some videos.
i see you have the geeetech …
any issues with that one?
Well, the build instructions were a bit lacking, looked like the instructions were for an older version. But they do have a forum you can post questions (bit slow everything must be approved - but you can search) and email support.
Seems like I spent the first month printing spare parts and upgrades. I have two sets of all the printed parts. Added a fan, since I print primarily PLA (due to odors) and auto bed leveling.
I also bought spares hot end bits, an extra stepper, and electronics. It helps when troubleshooting. Because you will have problems no matter what printer you get.
That being said, for the price, it has been good to me. Frustrating at times, and rewarding too. Additionally, it is upgradeable too.