How long does an iphone reset take?

I'm doing a complete reset on my 16gb 3Gs Iphone. It's been going for half an hour, all that is shown on the screen is the white apple logo, and every 15 minutes or so it will go black for a few seconds and then come back on, as if it's restarting. Is this normal? I hear this process can take a couple hours.others have said it will take only 15 minutes.

I jailbroke and unlocked it myself. It's runing the default 4.1 firmware.i'm trying not to connect to itunes and update firmware to the latest 6.1 unless it's my last option.

Any advice, tips, or comments would be appreciated. Thanks

Added (1). I'm still watching it do its thing, it's about an hour into its process. Its still showing the apple logo.

it just restarted again, but this time, it showed a screen of the battery being low for a few seconds, so it's changing its pattern, i believe this is part of it's process, because it hasn't shown an interface until then, only the apple logo.

it's been pluged to the computer the whole time to charge.plus it had a full charge when it started so i'm pretty sure it isn't low.

also how much does the apple store charge to do these repairs? I'm on very limited funds. (college student)

You've "bricked" the device. It has the booting path of an jailbroken device, but since it's not unlocked/jailbroken, it will continually restart. Your choices are 1) taking it to an Apple Store
2, restoring.

Mine took 5 minutes… Let it do its thing for another hour, if nothing, get it checked out.

I agree with Eric i did it in five mins. I would recommend going to apple store. You need to make appointment. If you haven't been to apple store before you're in for a vrty strange experience.

My iphone just shows the loading symbol