Time for some OOC planning to get some input and bounce ideas against the wall!
Depending on how much time and money we have to spend, there are a few options before the showdown:
Magewrights in Sharn can cast 1st level spells for 25G, and 2nd level spells for 50G.
We could purchase an Aid spell from House Ghallanda at 50g, to give three of us an extra 5 hp. Heck, if we get nitty-gritty with it, we could also buy 10 Goodberries off of them for 25g, which is exactly the number of berries we would need to top everyone off.
Perhaps the best item we could acquire right now would be a bag of caltrops, which could slow Garra's escape should they be in the fleeing mood.
Additionally, oil is cheap. It can be used to augment Ogham's and Alara's fire cantrips significantly.
All together that would be an expenditure of 76g2s (assuming two oil flasks)
The currier fee is anywhere from 5cp to 5g depending on the situation, but we are in Terminus, which has it's own Orien enclave (mostly for handling the Lighting rail, but I would assume other services would be provided their as well) It should be easy to get a line out.
Also, thanks to being in Terminus, we would not have to travel very far to get to a decent House Ghallanda establishment, and from there the Lighting Rail Station.