Yeah, I have an experience with my E1705: After almost 2 yrs of using the Dell battery, it was down to under 20 minutes and my BIOS was warning me of its low capacity. So, I bought an aftermarket battery. The battery was great at first. About ten months later it was equally dead, down to about 20-30 minutes of life. I ran it into the ground (kept using it until it finally literally failed) and then bought a new one from Dell. I remember it got to the point where I would unplug my laptop and it would immediately hibernate, for lack of power. So I didn't ever unplug it; and then one day the battery light on my laptop was blinking orange (iirc), and so the battery had completely died. I switched back to the low-but-not-dead Dell battery while I waited for the new one from Dell.
It's unfortunate, because I'm still pretty sure there are batteries out there that are cheaper while also being of equal or better quality. I don't see why that wouldn't be the case. But the problem is finding just which batteries are so.
I just went through my email to find more facts for you, rather than leave you with just a vague story. I have a chat log from 5/28/2009 where I asked Dell if my first, stock battery was covered under warranty; it was not, of course. I decided not to pay at the time, and waited a few more months for the life to get down to just about 10 minutes. Then I bought the aftermarket battery from eBay on 9/17/08 from seller "battery_laptop". It was $41.88 AUD + $25.99 AUD shipping = $67.87 AUD = $60.59 USD today, but back then it was a bit less. One year later, 9/2/09, I have a receipt of my $168.08 Dell battery order. It's still working very well to this day.
From an eagles' eye view you might think you can buy three cheap batteries for the price of one Dell battery, so wouldn't it be smarter to just keep buying cheap batteries? But no, there's a definite curve to battery life, and the Dell battery has a much gentler curve (if that makes any sense). There was a period of time near the end of life of both batteries where I just put up with being plugged in 24/7, and I know I reached that period of time MUCH quicker with the cheap battery. I put off buying the first new battery for a while, but I REALLY put off buying the Dell battery because of how much it cost.
Anyway, I hope this helps. Good luck! I'm certainly not vouching for the surely-overpriced Dell batteries, but if I were you, I'd do a lot of research and try to find a medium-priced battery to settle with. I think my experience scared me into running right back to Dell for my third battery, but if I were to need yet another new battery I wouldn't mind trying a different aftermarket one.