We did a 3 night cruise from Luxor to Aswan. We showed up in Luxor and walked the boardwalk until we found a boat with available spaces. We ended up going in to a small travel agency on the boardwalk because boat-hoping wasn't getting us anywhere.
We paid $50 per night per person and that included all meals which where quite good! This was not one of the best boats but it was pretty darn comfortable (big rooms, comfy bed), with a great staff, enjoyable guests, and fun entertainment. And all meals along with a comfy place to sleep included for $50 per day? Yeah, it pretty much kicked booty and was one of the highlights of our trip (and I'm actually pretty picky).
There is SOOOO much to see in Egypt. I suggest that you google Egypt Itinerary and you'll find a basic plan to work off of, depending on your time and interests. I also recommend picking up a copy of Rough Guide for Egypt - it is the travel book I used and was tremendously helpful.
Also, consider hiring guides while you are there, even if you negotiate with a taxi to take you around for the day. There are so inexpensive (when hired there) and can make for a much more relaxing trip. A good agency to fall back on is Thomas Cook; though not inexpensive you get what you pay for in terms of quality.
Our total cost for a 1 week trip, including airfare from Tel Aviv was $1800. For
everything, for a WEEK.
Nile is nasty - you wouldn't want to touch it let alone dive in it.
