How to keep scammers away from bidding/buying on ebay?

I'm trying to sell an iPhone on eBay. Keep getting scammer bidding or buying the product and not paying for it. They keep asking me for my PayPal email address. I told them to pay it with the Pay Now button, then they never pay or respond. I keep having to open unpaid item case and keep having to relist the phone. How do I keep away these people, so legitimate buyers can bid on it?

Simple. A fixed price listing with immediate payment required. If they don't pay the listing continues. See link below.

Set the buyer requirements so you don't accept overseas bids (most scammers are overseas) and you don't accept bids from anyone without a linked PayPal account as again most scammers don't have PayPal
http://www.ebay.com/...666/g.html

You will still get scammers but a lot fewer. The two biggest targets of scammers are phones and laptops

You can't. You can limit buyers to your country only. You can block bidders who have negative feedback. Put in the listing, serious bidders only, or immediate payment required. A bidder does not have to ask for your Paypal address. He will have it when he buys the item. Don't go outside of Ebay to make a sale. You can switch to fixed price instead of auction.