I don't think you were out of line at all. Sometimes the list price is unrealistic based on what your goals are with real estate investment. That doesn't mean that it's a bad offer. It also means that if it sells for 40k above what you were willing to offer to a person with no interest in real estate investing that you shouldn't be upset either. There's a price for every person and every scenario.
I would find yourself an agent who is willing to offer low for you as long as it makes sense. There are ways to do it. When I offer low, I provide a list of comps that support the ARV that my investor is looking to make on the resale side. Then I provide a list of rehab items along with their estimated costs that it would take to get that property to full market potential based on those comps. Then I provide a breakdown of what the holding and selling costs will be for my client: 6% commissions, 0.5-1% closing costs, holding costs for property taxes/HOA dues/hard money rates, etc. That helps them see that their offer isn't low on purpose, but that there has been a lot of thought put into it.
I've got properties 40-50k off list before. Just be nice and friendly when you are doing this, if someone gets offended then they are in the wrong business.