is it safe to buy on ebay im asking this for any kind of macbook, ipad, or imac. Should i just go by someones feedback and hope for the best or just look for the best deal?
Hope is not a strategy.
Need I say more?
Feedback
Never buy from anyone with "low" feedback. For "normal" sellers, ie less than 500 feedback, I would say anything below 90-95% should make you pause. For "power sellers", I would stick to 98% percent or better. But wait, there's more. Go to their feedback page and browse for negative feedback. If you see even one or two "took too long to ship", or "hard to reach by phone or email" consider looking elsewhere.
Paypal
Use Paypal. It allows you to claim a refund if you get a box full of dog poo instead of the iPad you paid for. Never wire money. Never mail money. Don't use a "proxy" service. Paypal is a legit proxy service. Sellers generally don't get paid until delivery is confirmed or you leave + feedback.
Avoid Bidding wars
Don't overpay. Don't sit there watching auctions that are about to end. Place your bid and go do something else. You don't need the item. You don't need the item. You don't need the item. If you don't believe you don't need the item, don't start bidding or you'll find yourself paying $89,895 for a $500 iPad in a bidding war.
Completed Listings search
Use "completed listings only" to search for your item to find out what people are really paying. Prices in red are items that failed to sell. Prices in green are items that sold. If all the prices in green are more than the money you have on hand, you will have to "get lucky" to get your item. More likely, you will wind up paying a scammer using a low price to lure you in. Be prepared to pay the average price in "completed listings" or walk away. You are not going to get an iPad for 50 cents from a seller in the Russian Federation who asks for a wire transfer and says "trust me".
Lay the groundwork
Make sure you are ready to bid. Many sellers require a "confirmed" paypal address. This is defined as the same address as the billing address for a credit card you have on file with paypal. Getting an address confirmed is slightly more complicated than the procedure for getting Israel to stop building settlements. Be prepared for a bureaucratic hassle to get a confirmed address set up with Paypal, but it is something you have to deal with for many ebay sellers.
Address confusion/delivery confirmation
Often, the USPS does auto fixup on shipping labels and in a few cases the address you want an item shipped to disagrees with what the USPS will allow. This makes it difficult for a seller to send you your stuff. Take some time on USPS.com trying to send yourself a package so you can see what they think your address and zip code are. This will save you a lot of BS with missing packages, etc. If you are offered an option, have your item shipped by UPS which isn't subject to the same address silliness you sometimes get when shipping via USPS.com. Always pick a shipping method that offers delivery confirmation if the seller offers that option. If not, perhaps you need to buy from someone else. The reason I mention this here is you want to make sure your address is recognized by USPS before going through Paypal's Byzantine labyrinth to set it as your confirmed address only to have a seller email you that they can't ship to that address using USPS.
Overseas Sellers
Don't buy from sellers shipping from China. It takes 4 weeks for your expected item arrival and you are already approaching the end of your dispute window.
Snipe
If you find you are losing items every time, try a bid sniping service. It will place a bid for you within a few seconds of the end of the auction and you won't be subject to emotional rookies sitting there overbidding you.