I want to openstreet map for my real estate project. Can any one help me..?

It sounds as if you might require more, and more customized, help than can be given in this forum. There's a list of professional consultants and service providers on the Wiki: http://wiki.openstreetmap.org/wiki/Commercial_OSM_Software_and_Services

You don't need to buy anything from OSM however you might have to do some things yourself. Remember, OpenStreetMap is mainly a provider of free data, not a provider of free computing resources. You will need

• a JavaScript library to display the map and markers on your page (e.g. free OpenLayers, free Leaflet)
• a source for the map ("map tiles") to be displayed - if it's for a limited area only then you can make your own tiles, but for larger areas you'll want to either set up your own tile server or use a third-party tile server (free offerings from MapQuest Open, commercial offerings from MapBox and Geofabrik, among others)
• a database filled with relevant OSM data to perform your proximity/nearby search (free MapQuest Open Nominatim service might do some but not all of what you need)
• someone to write the code that glues it all together