How to get product name and price through rss

i want to make a search on my website which content two fields one for keyword and the other for the city name selection,
now the question i get the product name and product prices againesed the search key word and the city name.without search in the database.

basics steps of my question
1 how to find the rss urls in the selected city
2 then how i read rss and made a search in it.
3 the data must not save in the database

Well i think your first problem is #1.
What do you mean ‘find the rss urls in the selected city’? Where are you getting your data from?