buying and selling

Let's say you're negotiating a bigger ticket item (eg >$5k) with a private individual you don't know. Is it appropriate for the buyer to offer (or the seller to accept) 50% up front and the balance on receipt of the item or is complete payment upfront the usual way to go?

Thanks for any input!
Payment up front is the general rule. However, there are a few good services, such as escrow services that can be used for higher ticket items. It costs a few dollars, but it does make the transaction safer.
It depends.

First one must take feedback into consideration.

If the seller has no feedback, I would be hesitant to send him anything but shipping, and pay COD.

If the seller has lots of positive feedback, then I have no problem sending certified funds to him. Just be sure you spell the deal out in email and save all the emails.

If both parties have lots of feedback or no feedback, well... anything goes. It may not be unreasonable to ask for 50% in advance. 100% COD might also be a viable alternative.

I try to buy items from people that have a lot of good feedback, especially the big ticket items.

I tend to try to let the party who has the highest feedback dictate terms. If someone that has little feedback does not like my terms, I pass on the deal.

I usually like payment up front, before I ship. Now, a very high ticket item may be another thing. I would go with an escrow service. It's money wisely spent. With killer feedback, I might do the transaction, with 50% up front, then cod. good luck.
If you are unsure then escrow or COD. If you are the seller, ask for cashiers check.