Limits are not only imposed on new accounts. Even older and in good standing accounts can get hit with limits.
If you plan on selling large quantities of goods there are a few ways of doing it:
Have a lot of stealth accounts
Buy yourself established accounts with higher limits
No such thing anymore as an "unlimited account". Even if your account shows no limits, you still have them but never maxed it out. A call to ebay will tell you what your limits are.
But, as for most problems, there is a solution. It's a complex thing and does require some time and effort but you will end up with an account that has very high limits.