Interesting discussion, because unlike most services, the prices of the most popular autoresponders have actually increased quite a bit over the years instead of declining. I was lucky to join and use a couple different autoresponders years ago and keep their lower pricing...
BUT I also believe autoresponders are justified in a way for their prices... it's big money. Email marketing is absolutely huge... I can write a broadcast in like 5-10 minutes, send that one mail to my list and make hundreds and sometimes thousands of dollars just from that. That's not even taking in account the automated follow-ups that can be set-up. I know for the size of my list I don't even make as much as others can/do from that because I just don't send broadcasts out that often... so in the grand scheme of things autoresponders are just taking a small percentage of the potential money on the table.. it's not their fault if you sign up for their service and never use it (send mails to your list). Without an autoresponder I'd make a lot less money, so why shouldn't they charge to make that possible?
I have many duplicate contacts, but seems like a necessary evil to me, just wish I wasn't paying for the same address more than once.
Even the most expensive autoresponders I believe you should be able to easily recover the cost and make great profits if you consistently build your list and send broadcasts/follow-ups regularly.. that's why people join your list anyway - they want to hear from you!