Hi,
 
Without knowing the total condition of either machine I'd venture to say maybe a few hundred dollars though I'd imagine the price of repair on your Miele added into the mix would largely infringe on your final profit.  Miele is popular legend and many people looking for a bargain will pay a considerable amount more on even one that's been used.
 
Electrolux too is popular legend, matter of fact one seller is offering a 7000 for $550 -- though I doubt he'll get it.  A careful buyer usually doesn't into legend and will want to know the cleaner is in tip-top shape from stem to stern.
 
Mellowing with age I guess, I'm more turned on by central vacuum systems than in the past.  A good system at a good price and properly installed should eliminate the issue of dust emission, noise, and cleaning range that you'd pay over a grand to get from brands like Miele.  You can tailor-make your attachment set and, if you ever decide to sell, I've been given to undertstand that a central vacuum might be an enticement to prospective buyers.
 
Venson

both the miele and electrolux 7000 are still under the factory warranty,why dont you find a warranty station that can repair them.Call the 800 customer service #,and you should be taken care of.
 
If your thinking of going central,tell us what type of home you have and then we can tell you how many valves you need and your best attachment options.
 
As far as EBAY goes sellers get a third to half of what the products cost new, and watch the shipping charges . Also buy from a seller with feedback of 99.7 or better.
 
O.T.