Average ebay price ticker

Hi everyone,

I want to show the average price of products on ebay so lets say

ps3 - $657.56
Wii - $345.23

So the way i see it is that i would set up the search criteria (wii,ps3) and a script would do a search on ebay for that keyword record all the prices for that keyword and divide by the amount of returns.

now this would be probably be a big drain on my server (if there was 20 different products for example) so maybe i could time it to execute once every six hours and show the results. for the six hours and then re search.

I looked into rss feeds not really what i was hoping for a want it to be a ticker so maybe the script should spit out an xml and the ticker will read it. the script will then overwrote it with updated info every six hours.

any ideas pointers would be a great help.
M