If you are unprepared and stuck 5 days walk into the desert ( next to a 7-11?) If there's a 7-11 you are not stuck and you don't need $10. What you have is civilization and phone and all you need is 911 if you are hurt or enough sense to call you mom / wife / husband / children / great-aunt tilly collect if you are not hurt.

OTOH, if you want to pose a scenario for use to exercise over then lets take the absurd as stated and rule out such convenient things as phones and emergency facilities and roads with friendly truckers for hitching a ride and to follow so we don't have to travel overland. What we have here is $10 worth of stuff that might have been procured from a 7-11 type convenience before we were summarily dumped 50+ miles in the desert with a vague idea of the direction home but nothing else.

Given the parameters of this exercise, a day spent without good direction due to inclement weather (sand-storm for example) could make the 5 day march into a two month ordeal of being lost. Just as we try to prepare around our homes for the remote possibility that we will burn it down with our children inside we might look at this scenario and consider the remote possibility that it might turn out to be somewhat more that a simple 5 day march in the right direction. Given this consideration I would want more than just "enough water to walk through the deser for 5 days" I might want to consider what I would need if the water ran out. I might want to consider what I would need if the ordeal lasted for a month. I might want to consider materials like tin-foil that I could signal to passing air traffic with. I might want to consider the ability to make fire to warm myself or to signal air traffic with or to sterilize whatever water I could find. Making an expedient shelter to keep warm or cool in the desert is much easier if you bring the roof. Digging the trench might be a hassle but you could probably find a soft enough place to dig with the help of a tin-can. Digging with your paws is going to get tiresome if not impossible. If I can walk through the night for 7 miles and then take 2 hrs before dawn to dig-in and throw a trash bag up for shade I can certainly make my water last a lot longer but the directional difficulties of traveling at night might ensure that I get lost in the attempt to travel this way.

Certainly knowledge is king. Without the knowledge to find direction by celestial objects at night you will be forced to march during the day. Without the knowledge of the habits of the desert birds your chances of finding water approach nil. Without the understanding of the need to stay out of the heat you are likely to dehydrate. Without the understanding of hypothermia you are likely to die in your shorts at night (even dug in you can die in 50 degrees of hypothermia). All of this knowledge is still only useful if you can translate it into action. Knowing that you need to dig a trench to wait out the day's heat is interesting but useless unless you have the where-whithal to dig that trench. Something like an empty 1 pound coffee can would do the trick nicely. Of course a military entrenching tool would be better but not in the budget of the scenario. Knowing how to signal a passing plane is interesting knowledge but if you don't have something shiney or can't make a fire you won't be spotted. Knowing that desert fowl will circle a fresh carcas and fly towards water in the evening is interesting knowledge but if you are blinded by the sun and can't look towards the sky you will not notice the birds patterns something like sunglasses or even cardboard with slits could make this possible.

It is neither the knowledge nor the gear but the combination of the two that represents preparedness.