UK charity seeks Facebook application for existing Organic Groups/D5 site

We are looking for a simple facebook application to expose our existing Organic Groups functionality on facebook. We need a developer with experience of facebook application development (and the facebook for Drupal application) who can quickly turnaround a simple application for launch by the end of June.

Go Help is the UK registered charity behind the http://www.charityrallies.org site. We run on Drupal 5 (planning a D6 migration in the autumn) with the Domain access module to provide for multiple domains. We have two active charity events, the Mongolia Charity Rally http://mongolia.charityrallies.org and the Roof of the World rally http://roofoftheworld.charityrallies.org.

Teams on the event have access to a heavily customised OG based system to provide for unique team pages. Teams also have access to a selection of custom cck based content types to allow them to blog, upload images, details of their vehicle and so on. We have a custom coded SMS bridge that allows updates to be sent from the road, and we use custom parsing to allow teams to tell us their location in the message.
You can see an example of this for a team who are already on the road: http://mongolia.charityrallies.org/en/unrealdoctors
Team Members are admins of the OG group. Members of the OG group are simply "team supporters", which allows us to use the notifications module to send out emails to all the team supporters whenever the team post a new message (either through the web, or by SMS).

The problem we have is that most people have facebook accounts and don't bother to sign up for a user account on our site, and receive updates from the team.

What we are seeking is a facebook application to expose the basic team functionality in a facebook application, so that users can subscribe to their favourite team through facebook and without having to create a user account on the Charity Rallies site.

I would be grateful to receive advice and quotes from developers who are experienced in application development as to:
(a) what functionality could be exposed; and
(b) for what price each level of functionality would cost.

We are a small UK charity with a small web development budget. However, we are happy, in addition to any agreed fee, to provide publicity for your company/development team. You can see an example of this on our site already for the excellent hosting provided by Hot Drupal, and the SMS gateway provided by AQL.

Best wishes,

Stephen Edwards