I'm in exactly the same situation. Here's what's been working best for me:
I run a Magtheridon raid every week with whatever guild members are available. For me, that usually means about 10 guildies and 15 pugs. We do gear checks, make people use ventrilo, and just make sure we're not inviting crap pugs. We can down Mag without wiping (although it took us a few trys to get there), and because of that success, I recruit anywhere from 2 to 5 people every time we do it.
Because it's so late in the BC raiding game, straight-up recruitment is near impossible for us. So I RL a mostly pug Mag run, and people are impressed with the efficiency with which we pull it off. We know the people we recruit are basically ready for 25 mans. It may not be a perfect solution, but it's been a great start.