how to filter search by values that are not available

As per the SolrQuerySyntax

Pure Negative Queries:

-field:[* TO *] finds all documents without a value for field

You can try:

q=(*:* -price:[* TO *]) OR price:[300 TO 400]

Try this:

-(-price:[300 TO 400] AND price:[* TO *])

is logically the same and it works in Solr.

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