Here's a suggestion for a weekly giffgaff podcast. I prefer audio podcasts but video could work too.
Every day Hazel has been posting industry updates from the giffgaff insights manager. They range from new devices, network shenaigans and whatever's happening in the mobile industry. Giffgaff has a lot of people that work in the mobile industry that can have a pretty good jabber about stuff like that.
Weekly topic. There's always something to talk about in mobile. One week a segment about mobile gaming, the next about 4g,the week after. Network backhaul, mobile security, community projects, Google IO or the new iPhone, developing mobile apps. There's really an abundance of topics.
One of the biggest reasons for giffgaff not to do a podcast in the past is the singular topic; giffgaff. Thre's only so much you can talk about and a single topic each week doesn't allow for much scope. The industry update and the giffgaff staff in the industry is an excellent opportunity for a broad, expert podcast that can focus on all things mobile as well as all things giffgaff.
The benefits are that it'd be good. Real insights from people in the industry about things going on in the industry as well as things going on at giffgaff. Also has the opportunity to get into podcast apps or iTunes and extend beyong the community as a reliable mobile news source.
The cost: Three or four Rode podcasters will cost you about £150 each, they're pretty much industry standard but the Blue snowball or the Blu Yeti are excellent microphones too. The best of budget microphones.
Probably a CDN to distribute the podcast. For only an audio podcast you're looking at a very low cost. Libsyn is a decent choice.