What we really need are 500 modestly wealthy people who pledge $2000 each per election cycle to provide $200,000 of seed money for each of 5 qualified candidates who are willing to run campaigns against bad Democrats in blue districts. The threat of a primary from The Left, even if it's ultimately unsuccessful, can be a great behavior modifier.
...adding, it's a bit tricky to do this institutionally. Ideally one would just set up a PAC and collect a bunch of donations and hand them out intelligently. But PACs are limited to $5K contributions to candidates, so that doesn't work. So you have to do the Emily's List model, which is using a PAC to solicit direct contributions to candidates. You basically need people to pledge to give money where they're told when the time comes, and and institutional structure which makes smart decisions about which candidates to fund so that people don't feel like they're wasting their money.
