I'm on PS4

Like xxxdcxxx mentioned you need to use the add-on called Master Merchant. You can get this from www.esoui.com and search for Master Merchant. Remember that once you have it installed and activated you will have to allow the add-on to attain records of all the items that have been sold throughout all of the guilds you are apart of. You need to give it at least 3 days of readings (log in at least once on 3 separate days). What this does is gather every single sale that has gone through all of the guilds and builds up a record of inventory/sales. This will allow you to actually gain a very good record on what items are being sold and at what price. The market sales fluctuate almost daily and this is why you need to get a good record of items.

Once you're ready to take a look at your items to see what the sales prices have been, all you need to do is highlight an item you are looking to sell. In that frame you will see at the bottom where there will be a graph. The graph will display the going market value to that Item. It will show you the lowest selling price, average, and highest selling price. Almost never trust the highest selling price because it usually has some ridiculous price you know someone who didn't know any better purchased that item for. Use your best judgement on what you price the items for and which guild you should sell them items through. This is because some guilds will sell more armor than raw materials for example.

When you teach yourself what options you can use within the add-on you will be able to really control what you want to see and how long you want the records to record for. I have my records saving past 90 days in order to see how much the market changes within a 90 day period. This gives you a much better grasp of what is out there and for how much.

I hope this helps...

BLOOD FOR THE PACT!

Yeah the only way you're going to do it is by going to lots of different traders. One way I check things is literally go to all the main cities, look for the same item and note down the best price you see. And then pick some random smaller/lesser known guild traders and see if the prices vary much. That way you can get a good sense of what the price should be.

If you're in a friendly trading guild, you could just ask a few people in there what your items might be worth.

Also check the guild sales history tab (I assume you have that on PS4), for the guilds you're in, see what items are being sold.

Hope that helps!

Do not sell trophies, psijic recipe fragments and treasure maps through your guildstore.

The horrible ancient potato UI design we have don't allow search for those items without addons, so if you set them for sale in a trading guild, other players must browse 300 pages to get to them... it will never be sold, unless your guildstore only fills 2-4 pages that players can browse through.

If you are in Multiple guilds you can go to your social tab and go to the guild section and look at the sales of each of your guilds. this will give you a good idea what sells and for how much. I find i can price things a couple thousand more in one guild over another. I also found this web site is a good resource. https://esopricecheck.wordpress.com/
While it is xbox and you are PS4, i find its a good Starting point. The Prices are higher on ps4. Hope this helps