If someone doesn't answer you...

What's a fair amount of time to list what they had supposedly bought from you if they don't confirm their purchase?

I wanted to give them at least 48 hours (and 2 pms) about their items, but I won't send out items unless the recieving party confirms it...

I would check their page and see when the last time they were online. For me, if they've been online consistently, then I will only wait 72 hours (3 days).

they were last online 2 days ago.

Wait and see then. If they haven't even been on, give them a chance to log on and see the messages.

Sounds like they wouldn't have had a chance to read any of your messages if they haven't been online for that length of time. Definitely don't send out the items without confirmation just in case something's come up and they don't get online for a while (or at all). If they have been online without responding, then it's fair to look for another buyer, but since they haven't I would maybe wait a few more days at least. Depends on how desperate you are to sell.

About 72 hours if they've been online, up to a week or two if they haven't come online at all. Worst thing that can happen is you can say you didn't think they were interested and resold it (which if it were me, I would understand). I always try to message them about a week in to remind them, because I have a terrible memory and sometimes forget what I've bid on myself, and have days I only get on EV through my phone.

If they haven't been on, wait, like previously stated. Some things may have come on that caused the person to not come online. (Ex. internet is down, personal problems, etc.) Maybe send them a message or two while they are gone, but don't wait forever of course. No longer than a month, unless you don't mind waiting.

If they have been on, however, and you've messaged them, and they don't respond for at least 3 days, sell it. Its obvious they are ignoring you, or are no longer interested. Perhaps even message them and give them a warning saying you will sell the item in a certain amount of time. Maybe then, they may message back, or maybe they won't.