You have only two realistic options for selling direct: Adobe Content Server or no DRM. ACS is widely used and widely hated and completely compromised. It's also expensive. You could go through a third party aggregator to lower the cost but they may not integrate with your Perl shopping cart.
Or you could distribute through iBookstore or the Kindle store and lose 30% of the sale.
Or you could distribute through iBookstore or the Kindle store and lose 30% of the sale.