It is really cheap. If I purchase one, when do I tranfer it to other domain registrar?
Vultr, Digital Ocean might be your options.
Webxen, Hostug, and Hosthex are $6/year, but I never try them. If you go with these, I recommend you to back up frequently your website.
You can try Linode.
NameSilo is the cheapest domain registrar. namesilo.com/pricing.php
Vultr and Linode are good options, thier server plan with $10/mon is suitable for your needs.
You can try Vultr, DigitalOcean, and Linode, they have a good reputation among China customer.
There is a list of free control panel:
Separate names with a comma.