Multiplattform mobile App to manage a customer database

SUMMARY: We require a PoC for a mobile application to manage a customer database (aroundme-like) through GPS coordinates, a live-demo will be appreciated. BACKGROUND: The customer information is stored in database, containing about 500,000 customers. We have an already working aplication developed in ASP.NET web forms so there are some webservices (that we'll provide) linked to this web-app to get all the data needed to find the near-places of interest and customers information. PROJECT: We have a HTML5 implementation (jquery mobile), but We droped that version due to performance and user experience issues. So our main focus for this PoC is about design, USER EXPERIENCE, fancy and friendly usability. We want a fresh app, not a 3-years-like app, so a good and attractive DESIGN is a must (swipe events, transitions between pages, pull to refresh, infinte scroll, any good idea a user will want, ...) Despite of we used jquery mobile, it's not a must, so feel free to change the framework you better consider, or even go to native apps (which initially is not our first option) . REQUERIMENTS: This app is intended to be used by a corporate field sales force. In a sense it recalls a CRM. Style and user experience should be professional; yet corporate users are used to consumer apps so it should rather be a “sexy, sleek professional style” than a “boring professional style”. For example, one project might be to visit certain “prospect leads” (that is, potential customers) along a pre-defined route or list (particular to each user). During the visit, the user would get information from the lead (like number of tables, menu price, etc…) to qualify it, in order to later calculate which leads have higher sales potencial, re-visit only those, etc… In another example, a team would be assigned areas in the city. They would need to visit and qualify all the points of sale (POS) in the area, filling a questionnaire for each POS and checking the basic information (like name, phone number, and GPS positition). In another project, the sales team might visit periodically their current customer base, in this visits they would qualify the lead as well as try to introduce new products… But some of their time should be used to find new customers, so an around me functionality is needed as well. This “around me” could (??) be interpreted as a “Checkin” as in Foursquare or Facebook places or Google local. In all of the above example, new Points of sale might be found during the task, and should be easily added and geocoded in the app. So, basic requirements are: listing or mapping customers around me, filtering by multiple criteria (like customer type, price range, city, name, phone number…) , view and edit customer details, add a new record… CONSIDERATIONS: We're looking for an experienced, reliable, up to date in the mobile state of the art, proactive and easy-to work person. This PoC is important to see if we can handle our performance requirements and UX with HTML5 or we have to go native, bu the main goal is to to evaluate the person’s knowledge and ability to execute. We are looking for someone who can help us is mid-term for a bigger project, so if the performance requirements and UX are reached, our idea is to externalize the full implementation of the project (which covers a wider range of apps). As such, we need someone with the ability to design an execute – that is, we don’t need a graphic designer whit no ability to program the app, and neither do we need a great app programmer, if the final design is very basic or old-fashioned. App performance is a must, so ideas in the right direction (like server or local caching…) would be appreciated even if not implemented in the project. OTHER: About the project budget, our lack of experience doesn't let us know if the budget is too high or too low, please take it just as an idea and feel free to post lower or higher bids if it is under or overestimated. David.