Hello.
I am a GIS(Geographical Information System) expert and Web&Mobile(iOS&Android) developer.
Since 10 years before I have been developing GIS applications.
I graduated GIS special education course and I have rich experiences for development Desktop,Web and Mobile GIS applications.
As a GIS developer, I can develop any kind of GIS application based on ArcServer,GeoServer and GoogleMaps,OSM,MapBox,OpenLayers,PostGIS and PostgreSQL and MS SQL.
And I have many Web technologies such as PHP, Java,C# etc.
Your budget is very low but I can help you. I have two project like similar this. I think your marker locations are stored in MS SQL database so I suggest you would prefer Geo-Spatial Data base
thank you.