Hi Nasseem (and Sol),
Hmmmm, a tricky one.
Personally, I think I would not provide a "per print" price, it strikes me, with friends/family, as being too commercial, and there are other downsides I'll cover later.
I would come at it from the the angle of "what did it cost me?", so if you are paying for the printing, obviously charge that on at full cost, maybe evening adding 10% (for your time finding a printer), also add on any direct costs involved like going there to collect the prints, etc.
Regarding PP time, I think I would 'conjure up' an hourly rate based on what I am paid at work (a totally unrelated area, I know) and use that multiplied by the time involved in PP to arrive at a figure, keep both the hours and the rate to yourself.
If you feel bad about how long it took you to PP them (given your inexperience) and that has pushed the price up, then make an adjustment on a 'what feels right' basis.
Shooting time; I would only include this
if they initially asked you to take the pictures. If you asked them; e.g. for practice, then you wrote that cost off there and then, so to include it now would be taking advantage in my view. If they did ask you first, then apply same ideas as for PP time.
I'd present the two as separate items;
$xxx for printing, saying it is mostly what you paid the printer, and
$yyy for PP (and shooting time if approppriate)
Make it clear (but also don't labour the point) that this was a one off deal on account of the circumstances.
Don't pre-empt and start discussing 'next time', it will either ensure there isn't one, or you may regret what you say now because of what you know by the time next time arrives.
As you haven't given them an hourly rate, or said how long it took you, that leaves you clear to 'up' rates a bit more in future without cries of "last time you did it for so much an hour", etc. and avoids comparisons with other places.
For any future event, consider a more commercial approach as outlined above by Peter and John.
EDIT: One last thing; and I very recently fell into this trap myself, when someone says, "I want all of them",
don't do it, 'lose' any sub-standard ones
and don't have several identical ones; pick one (of a certain pose) and go with it. Being personally connected and proud of them, if they show them to other people, the casual observer will be thinking "why so many the same?" this is boring, and switch off - you have instantly harmed your reputation.
Hope that helps,