I'm working on the theory that it's ok to self-publish as a stepping stone to traditional publishing as long as you follow that up with a track record. If a self-published author can approach a new agent/publisher and demonstrate that on their own they've managed to achieve a couple of thousand sales, that should give the agent/publisher confidence that you are a sound investment. Shouldn't that actually give you an advantage over the unknown quantity of an unpublished submission? I hope this is sensible anyway, as all my eggs are in that basket.
I self-published Nature Mage in September of last year, but due to production issues it wasn't selling till January. Since then I've done 9 Waterstones signing and a couple of school visits, and have loads of quotes from teenagers saying how much they love the book. I don't know exact numbers but sold around 600 in the first half of the year and now have consistent kindle sales in the states - not high numbers but they just keep selling virally through Amazon. I'm hoping that if this carries on, and 600 moves up to a couple of thousand, that I might stand a chance.
Having said that, I received two agent rejections this week and got a couple of stinking reviews on Amazon which water down the good ones. It's tough having your work out there. It's like someone stomps on your heart every time you get rejected. If I peer intently at my skin I think I can actually see it thickening!