Advice desired- Offered chance to shoot event

[Dominantly]

So I was approached today by someone I know, asking if I would be interested in signing on as the photographer for the company Christmas Party.

Apparently what they want is one 5x7 photo of each couple, as they come into the party. They would like for the prints to be available for the people one week later.
They will pay for the printing, and inquired as to what I would charge for my services. I have no idea what would be reasonable seeing as how this is where I work. Not to mention, they will have anywhere between 200-220 people (family as well). That's a whole effin lot of people is my first impression!
I saw photos from last years event, and they were marginal at best, so I am fairly certain I can beat that quality, I'm just leery of the amount.

Equipment I have for the shoot:
Wescott TD5 Spiderlight
SB-600 Umbrella
SB-800 Unbrella
Muslin Backdrop
D90
-50 f/1.8
-85 f/1.8
-105 f/2.8

I could probably get my hands on a D700, not if it would help any though.


So what are your thoughts on a price? Anyone ever done a similar event? Insight?


Thank you in advance!