We looked at this last year and my IT partner got it to work to a fashion.
He found that he could take RM info and generate a mash up. Please excuse my lack of technical knowledge.
However, he could not look back at historical changes. So the information started from the point of the first search. Subsequent searches were then used to form data base of time on market and price movements. As we were looking at using this on a large scale and intending to get flagged depending on our set criteria, it meant searching RM every day over, lets say, the whole of the South East.
Then RM got wise and restricted his access and he was no longer able to search the site as required. RM monitor the number of searches performed and they cotton on to high number of searches in a small space of time. Whilst he felt he could get round this the amount of time and effort to to do so was counter productive. And of course it would be a constant battle to stay one step ahead of RM.
But you can / should be able to do this on a relatively small scale. Which is probably what the previously mentioned web site is doing. The trouble is unless you happen to notice the first day a property appears then you are potentially not getting true results.
From my experience in the current market, just ask the EA. As long as they perceive you as been a true investor they will give you the info. If they wont then simply move on to the next.
Good Luck.
Andy
Go Go Go..........................
http://www.BlueMarbleProperty.co.uk