Total newbie question

So Hey all.
I'm looking forward to receiving my first 3d printer very soon. I'm totally new to all of this, other than research I've tried to do here, on youtube, and on thingiverse. My basic plan is to get the printer up and running, then downloading a few published projects to try before even attempting to learn how to design something on my own.
Anyway, for my initial purchase of filament, I was thinking of a sampler pack from makergeeks (http://www.makergeeks.com/mafisusapak.html) just to see what colors I thought would work, and so on.
I really have no idea what kind of filament consumption I could expect from what I'm up to though. I was thinking after a good calibration, I would attempt an Iphone 4 case or a small toy. Is 3m of a single color enough to accomplish any of these?
I will be working with a German Reprap Neo. .5mm nozzle takign 1.75mm PLA.
Any help here would be appreciated. This is going to be a very interesting road...

Off the top of my head, I'm thinking 10m or so for a phone case (could be wrong)...

Thanks man. Even if your off by a couple meters, you're telling me what I need to know.

To find out how much filament is needed to make an object:
1. Run the object's stl file through slicing program so that the Gcode is generated. You will have to input set up the slicer to suit your printer's specs, which is a task you would have had to do anyway.
2. Run the Gcode file through interface software such as Pronterface, or similar. When this software has worked through the Gcode, it will tell you how much filament will be required to print the object.

Old Man Emu

Slic3r and Kisslicer (and probably others too) put the volume of the filament that will be used into comments in the gcode file. I usually take that value (specified in cm3) and multiply it by the density of the filament (g/cm3) to get the mass of the filament that will be used.

Length of filament is difficult to measure when you have a partial spool. You can keep track by maintaining a running length of filament, but in order to verify what you have left, you'd have to unwind your spool. So I use mass -- I can just weigh the spool before I print anything and weigh it periodically to know how much is left. This is particularly helpful on larger prints or when the spool is running low.

If I don't have enough, I can estimate how long it will last in a print. When I get to the tail end I can pause the print (through whatever host software I am using), pull out the tail end of what's left, and load up a new spool before resuming the print. I also raise the nozzle so it won't melt what I am in the middle of printing while I am changing filament. I don't know if it's necessary, but I set the temp on the nozzle manually when I pause the print so that when it resumes it for sure hasn't lost heat.