$20 for the VPS & Cpanel?
That is completely unrealistic from any reliable provider, that will still be in business several months later.
If you get luckly, then you might find a provider to sell such to you at cost, just to build up their reputaton.
Jump that price up $10, and then you'll be able to find what you are looking for.
Why do $10 shared reseller accounts come with unlimited cPanel/WHM - but $20 VPS accounts can't offer it?
Because a shared hosting or reseller account uses the server's license which carries no incremental fee. If you have 2 shared/reseller accounts on the server the server license fee is the same as if you have 2000 shared/reseller accounts on the server. However, every VPS has to have its own license, thus its own fee.
Providing Managed VPS for over 11 years Managed Dedicated Servers for almost 19 years! http://www.servint.net