You probably want to ask what they're willing to pay for the print. Depending on how you get it done, the total could come to $10 or less, or well over $100; with that much variety, you definitely don't want to shock them with a huge price tag when they were expecting something cheap, or on the flip side leave them unsatisfied with the quality if they were expecting (and willing to pay for) fanciness.
Cost of the print will vary wildly depending on what size you want to get. Anything larger than tabloid size (11"x17") will have a pretty severe jump in cost-- you can go to places like Staples and FedEx Office (once Kinko's), or similar local alternative printshops, and get artwork printed off at that size or at 8"x11" for anywhere between $.50 and $2.50 depending on paper stock. (They usually offer multiple paper stocks; for what it's worth, I like getting my artwork printed on fairly heavy photo paper with a Satin finish, since it's got a little bit of a sheen to it without being as fingerprint-sensitive or, er, glossy, as most Gloss finishes). What's most important is that it feels good to you and shows off the detail that you want to see.
If you want to ramp up past the 11x17 range into the larger sizes, poster-print, etc, the price will jump to somewhere around $20 at the low end and..... actually I have no idea what the high end is, somewhere in the hundreds I'd assume (if you wanted the print to fill a wall). There are some online printers that will handle this sort of thing, and their prices can be pretty good; the major drawback of online printers, though, is that you don't really have the same option for back-and-forth with the printers (ability to flip through and feel all the paper samples, ability to tell immediately if your colours are printing wrong, etc). Staples and Fedex do offer +tabloid printing, at a cost, but from what I've seen (depending on the branch) this tends to be more suited for signs and billboard displays than for art pieces.
If you want to really get fancy, you could do a giclee
art print, though that would involve a serious hike in cost.
Personally I'd suggest the 11x17 option and matting it into a nice frame (or just matting it and mailing it like that, to cut down on shipping costs). Definitely make sure you have a good scan (sometimes things like fingerprints and bits of eraser fluff that are invisible in a web-sized file are blatantly apparent in print, particular if the image has lots of light areas), and that you (and your daughter) are satisfied with the resulting print before sending it off, though.
(Apologies for tl;dr; I'm procrastinating on homework and for some reason it is making me much more inclined to wordiness than usual)