The Michael Jackson estate just laid the smack down on a bunch of Michael Jackson wannabes -- all over access to Neverland.

The wannabes are actually in a Michael Jackson tribute band named "Neverland" -- a name the MJ estate feels is a violation of its trademark.

Long story short -- the MJ estate wrote a scary legal letter demanding the band change its name ... and it did ... to Foreverland.

Here's the catch -- "Foreverland" still owns the rights to the domain name neverlandsf.com -- and its willing to give it back to Camp Jacko ... for a cool $30,000.

In short, the Jackson estate told the band to "beat it" -- and gave them until February 2011 to begin forwarding all web traffic to the new foreverlandsf.com ... or else.

The band tells us they're currently going over their options.