Charity needs the perfect map/locations plugin – please recommend!

Hi guys – Thanks in advance for your help & advice,.. I’ve found a few solutions close to what we need, but nothing perfect so far!

I’m currently searching for a suitable plugin to use with a re-development of http://www.suspendedcoffees.com to upgrade from a text listing system to a nice interactive map based system showing participating businesses near you(With text listings below maybe)

The organisation is run as a non-profit by volunteers so I’ve been tasked with making the new website as self managing as possible – so we need:

1. New cafes need to be able to sign themselves up and add/manage their own location/contact data (New signups to require admin approval before the listing goes live). This process needs to be simple and intuitive.

2. Our current system contains the details of over 1000 participating businesses which we can export to a csv file,.. we need to be able to import these to the new system.

3. We were also hoping to make the front end of the system very user friendly – having a map system which can automatically detect the location of the device its displayed on (it doesn’t need to be very accurate – a location within 10 miles will do) centre the initial map display on that location, and display a radius of perhaps 50-60 miles highlighting all participating businesses in that area would be perfect.

4. The plugin needs to be responsive, touch enabled and interactive – scroll and zoom so users can browse participating cafes worldwide.

5. We need a search feature – search by keyword and search by distance.

6. Walking/driving directions to your chosen cafe would be a bonus, but not essential.

7. It needs to be simple to install, setup and administer – – I’ll be doing the most of the work getting it live on the net, but the guys running the site on a day to day basis are novices at best, so zero coding on this one!

8. It needs to be bulletproof and self contained – the main reason for the current re-design is that the current site has become unstable due to being built with over 40 plugins which have started to conflict due to people clicking the “update” button. The new site needs to be much simpler and rock solid stable.

9. It needs to be able to handle a big database – we have over 1000 cafes already and the organisation is only a year old,.. we hope to break the 5000 participating locations mark by the end of this year and ultimately expect up to 50,000 locations to be listed.

10. It needs to be cheap – this is a non-profit organisation – we don’t charge for listing on the website and are supported entirely by voluntary donations. We’ve a small bit of cash to spend getting this right, but not a lot!

Currently we love this one – but it doesn’t have all the features we need: http://codecanyon.net/item/progress-map-wordpress-plugin/5581719?ref=codespacing

Can anyone recommend a plugin that will be perfect for us, or one where the developer is able to custom code the additions we need at a reasonable price?