Hi Shah and welcome to forum,
I can't personally speak for everyone, but I'm doing just fine thank you!
In regards to selling on eBay. No requirements at all, other than following their rules. You're only legal requirements as such, are to the tax department. So if you are doing this as a business that will be declaring your income derived, you really should speak with an accountant to ensure you know how to maintain your books.
Cheers