Power supply wiring

I am almost finished building my 10" i3v. I'm ready to wire the power cord up Sunday but I have a question. I didn't know I had to order the power cord when I ordered the printer. First let me say that is one of the dumbest things I've heard of. Why doesn't it come with one? You don't have to answer that, it doesn't really matter, what's done is done.
Anyway, I went to Home Depot to buy a power cord and the only one they had was pretty light duty so I asked the dude in the orange apron. I told him I needed to wire it up for a 12V, 30A power supply. He tried to sell me cable that was almost as thick as my arm (exaggerate much?) that was $4/ft, plus a $20 plug. Then he said I needed a $25 female wall plug, and needed to run new romex from the new outlet to a new 30A breaker in the panel. Ok, I don't think many (any) of you have spent $300 to wire up your printer. I bought a heavy-duty, 14 ga extension cord that I plan on cutting and using for my power cord. I think this is what I bought http://www.homedepot.com/p/HDX-6-ft-...-711/100672773

I don't have to upgrade my electrical system to run a printer, do I?

DrBoost, Don't confuse the 12v 30amp DC output with the 110v AC input. The AC side is considerably lower amperage than the lower voltage DC output. The input specs on your power supply should list this and it will probably be under 15amps. So a standard power cord and wall outlet should be fine. Take a look on the power supply info tag and it will list the input requirements and that's all you have to worry about for the wall plug side of the supply.

Yes, there is no way your pulling 30amps. On A 120v circuit aprox 1500-1800 watts is max on a 15amp circuit. Your printer when pullingax is prob only 300-400 watts. You need to take into acct some line drop as well so the lo ger the cord to your printer the bigger gauge it will need to be. To your power supply though i would take a guess that a standard 14/3 wire would work. But an extension cord, cut the female end off and wire it into your power supply. For a higher grade cord get a length of soow 14/3 with a nice male end and wire it up.

Thanks guys. I KNEW there was something I was missing. The extension cord I bought is a 14/3 so I'll be fine. I appreciate it.