I'm very new to HTML programming and I have a more advanced challenge on my hands. I'm developing a website that will feature pricing information provided by individual price-spotters from across the country. These spotters will log in to report prices by typing those prices into boxes for each retail store location (see www.gasbuddy.com for an example of a similar process, where spotters are entering gas prices).

Since I'm operating on a very, very small budget (and I have no experience developing this type of site with data), here are my questions:
1. Is there some simple, off-the-shelf software application that will allow me to build a data box for each retail store (50,000+ individual stores) and then populate those boxes with the name, address and phone of each store? I plan to get these data from a commercial online yellow pages provider, so it'll need to interface with them, so I don't have to type in 50 thousand stores!
2. What are the best solutions/programs/applications to set up a member control panel and functionality, to allow price-spotters to input these data into the appropriate boxes - and track the number of posts, etc.?
3. How could I allow data to be streamed or downloaded from a commerical data provider - to provide data for stores where spotters have not recently entered fresh pricing? Again, any suggestions for steps, tips, techniques to accomplish this?
Appreciate it!