The entrance fee to Ms Clinton's 'grassroots' conversation campaign is $1000 - $2700.

[dlwickham]

161. but he's never run as a Democrat

you're missing the point

this is straight from his congressional website

Bernie Sanders is serving his second term in the U.S. Senate after winning re-election in 2012 with 71 percent of the vote. His previous 16 years in the House of Representatives make him the longest serving independent member of Congress in American history.

He says he's an independent and has run as an independent in the past.

Patrick Leahy's site says he's a Democrat

Patrick Leahy was elected to the United States Senate in 1974 and remains the only Democrat elected to this office from Vermont. At 34, he was the youngest U.S. Senator ever to be elected from the Green Mountain State.

This article states pretty clearly that Sanders has never been a Democrat

http://www.realclearpolitics.com/articles/2015/04/30/bernie_sanders_joins_2016_field_--_as_a_democrat_126448.html

But, until Thursday, Sanders has not ever been a Democrat in name, and he has been proud of that distinction. Since Sanders first ran for federal office in 1972, he has identified as a third-party or unaffiliated candidate.

In his first bid for Senate, Sanders ran under the Liberty Union banner. When he successfully ran for Burlington mayor a decade later, he identified with the Progressive Party, which he launched in Vermont with that race. Since 1988, when Sanders unsuccessfully sought a seat in the House of Representatives, he has run as an Independent.