6 yuan per orange!  I think you've paid quite a substantial amount of "waiguoren tax" there.

It depends in which city you are. And you also need to make sure the fruits are well in season first. Then go to three or four sellers to check the prices of a few fruits. Just make it like you aren't interested and just asking nonchalantly. It's important that the sellers aren't next to each other or even don't see you asking the price to the other sellers. Once you get an idea of the current average price of a few fruits, make sure it's ripe. Then make sure you take the plastic bag full of fruits and go next to the scale and then give it to the seller. You need to make sure the scale has the quoted price. If you aren't quick enough to check the price, don't feel shy to put the bag back on the scale and take your time to check the price. It will sometimes annoy the sellers if you do that, mostly those who want to put the price a little bit higher, but at least you are making a bit sure that they aren't ripping you off. I always avoid sellers that don't have electronic scale, because it's more accurate, but then again, they also have little gadgets that wirelessly modify the units when weighing

well seems you got ripped off, unless you bought "import" special oranges. paid around 6 rmb for 5 oranges last time

I can just agree with you. I found fruit here way more expansive than back in italy, and the price you paid seems "fair" to mainland china. That being said that the quality sucks.

hope they were good, sounds very expensive. 

Good tasty fruit is really expensive here, while you can also buy very very cheap ones. some of the cheap are tasty too, some of the expensive are not that good. its mostly about the luck and if you make a friend with the shop owner, he can always give you the good ones, as I do here  :)

Buy fruit in a supermarket where it is fixed displayed prices. You can compare it to your trusted street vendors then if you want.

Also know which fruit is grown locally.

Yep, buy in the supermarket. I bought three Australian oranges for 24 at a "luxury" grocery store, as a going-away gift for a friend. The oranges were the same I get back in WeiRenstan but just a tad more than expensive. Actually that price seemed fine as I was buying it more for the packaging since quality packaging is of course the way to impress locals here. But in a local market that's a tad of a rip-off, I just think of these small rip-offs as learning lessons for how to avoid much larger rip-offs.

Most kinds of oranges are out of season right now, the price should come down a bit around December - January. Add to that the fact that most of the oranges right now are coming from Australia, South Africa and the Americas, and you will see why prices are in the teens and above per 500rmb. I generally buy my fruit from Pagoda or BaiGuoYuan,  their fruit is a bit more expensive, sometimes cheaper, but 9 times out of 10 tastes better, and they let you taste it in the shop and return it if you aren't satisfied.

An orange is usually 200-300 grams, so if the oranges are going for 15 rmb per 500 grams, you can expect to pay more than 15rmb for two oranges, sometimes a really big orange will even pass 500g, so if you have 8 oranges it will stack up quickly. 

The only fruit I have noticed to be significantly cheaper at home than they are here are Kiwifruit and apples, but we export both of those on a fairly large scale so there is plenty of spare fruit that is not pretty enough to send over here to China so has to be sold at home, my mother worked at a kiwi fruit orchid for a few months (seasonal) and he job was literally sitting at the conveyer dividing kiwifruit into three boxes, for export, rotten or spoiled fruit, and ugly fruit to be sold locally. Anyway, off the point..

I remember in Beijing I usually bought oranges for between 3 and 6 rmb per 500 grams depending on the variety. That was during winter, I have never had a summer in Beijing, so can't compare. 

I have found that a lot of fruit is more expensive here in Shenzhen, but some varieties are cheaper, I guess it depends on how far they need to travel and such.

One thing to remember, is that they give you the price per jin, 500g but when they weigh the fruit often the barcode printed has the price written per kg, which means it will be double, don't be alarmed, if it says its per kg just divide by two to make sure you aren't been ripped off. 

Get coupons they will reduce the amount that you have to pay....also the type of orange. Some oranges are more expensive than others...

Um, dude/ette, I used to buy bags of like 20 oranges in Changsha for like 15-20 RMB. Sometimes I could haggle them... yeah, like Kaiwan said, you got charged the "waiguoren tax."

Don't ever go back. Punish the cheater.

I should add that, yes, 99Silva is right about some types of oranges costing more. Imported oranges cost an arm and a leg, but as for his coupon thing... I've never heard of that, nor have I ever seen them in China.

In Hunan, I did not have any problem buying cheaper oranges all year long, unless I went to stores which claimed to import them.

I find fruit to be very expensive here in dongguan, even in the supermarkets. Usually though they have local fruit and import fruit, local kiwi 2rmb imported kiwi 8rmb. "Waiguoren tax" I don't believe in, I have never been ripped off here, in fact I usually get a lower price than the locals.