It's always nice to hear of new independent business people interested in opening up in Marple.
The business rates in Marple are slightly higher than you would find in some other District Centres but that is because of the strength of Marple's shopping centre. I believe Marple has the lowest unit vancancy rate of all the Stockport District Centres.
The £9,000 sounds like the Rateable Value. There is a multiplier that gives the amount you'd actually pay (off the top of my head i think it's something like 0.419). Also, depending on the size of your operation you may qualify for Small Business Rate Releif. Having said that, as your expanding your empire you're probably already aware of this.
I don't want to post to much on a public forum incase I accidentally give away some confidential information but if you'd like to discuss 'business in marple' please feel free to drop into my shop (Paul Howard, 50 Market Street) or drop me an e-mail (marketing@marpletraders.co.uk).