I right price for the pair in the condition they are in is $500 for the pair (being "fair" to the seller & to you). Some people will say more - some people will say less but a real world price for the pair as they sit is $500 max.
Once you put 6 to 10 hours into each of them they are only worth $800 for the pair shopped and working 100%. And you will have at least $50 into rings, bulbs, etc.
So if you spend 15 hours on them to "make" $250 on the pair you are working super cheap but that is about where the math will end up. And it will likely take you a month or more to sell them for $800 once you are done with them.
I run all over the PA, NJ, MD, DE, WV, NY area buying machines and for me to drive for them and move them out of someone's basement I would want the price for the pair under $400 (and I would likely make an offer of $350 on the pair) if I was the buyer. On the average I buy about one machine a week so I must be paying enough for them because I don't even advertise that I buy machines. Most of my contacts come from people I have done business with in the past referring people to me.
If you are looking to help a friend out pay $500 for them, if you are looking to be "fair" to yourself and want to make a few dollars selling them $400 to $450 makes more sense. And if you are fine working for free and really want to pay near market value then pay $600 for the pair but anything more and I think you will be sorry in the end.
Just my 2 cents on things looking at it from the eyes of someone that knows the local market fairly well. And for any of you guys that think they are worth more come see me at the Allentown Show in a couple months. I'll have a couple dozen EM's in decent shape under $400 each.