Se my blog for the reason my open house is so expensive http://www.trulia.com/blog/david_chamberlain/2008/12/how_to_
Good luck :)
Here is my personal experience - My admin assistant spends 2 days worth of work uploading listing to correct sites and doing brochures (that cost about $5 / brochure on top) and then target mailing/ mailings ,staging then constant update of price and changes on those sites to keep info fresh. I highly syndicate my listings. Then doing an exclusive site for listing - feedback site and list goes on and on... I would say as soon as listing is taken there is an upfront cost of $1400+ and then ongoing cost. Listings honestly can be less lucrative money viset but I believe they make the business go and love to get them and Market them. No matter how highly the listing is marketed it will only sell if it is priced right and shows well n Marketed right off course. So I would say lot of energy money and time is taken when and before a listing is put on the market :) They are fun journey these days...though..
OH BTW Realtor and association costs are always spread.
But to answer your question, I would estimate *average* marketing costs for an *average* property to be between $500 and $1,000 (that's not including the fees we pay for MLS, association dues, etc.).