Okay, so i've only fairly recently got hold of Morrowind and played a few hours in it. Finding it a bit hard to get into to be honest. Anyway, my question...

When selling a bunch of items to a shop it seems as though I have to manually add up what they are all worth to know how good or bad the shop owner's offer is at the end of the transaction and how much I should try and haggle. Am I just being blind and not seeing where the actual value total is, or some idea of what percentage the shop owner is offering me? If I've just come back from a dwemer ruin weighed down with all sorts of various bits and bobs of different value and I try and sell it, all I get is a flat gold offer with no other information. Do I REALLY have to grab my calculator to work out the percentage he's cutting off?

The ammount they offer you is based on your Mercantile skill, and their disposition to you. You can haggle with the + and - buttons next to their offer. The ammount you can haggle is weighed as a percentage of the item's base value. So haggling on items with low value will likely result in the offer being refused. Asking for 5 extra gold on an item they offer 10 on might not work. But if you ask for 20 gold on something worth 100 might. You can individually sell items, and this is in fact a better idea.

Yes but.... items have an inherent value which you can see when you click on them right? They offer less than this. All I'm saying is if I'm selling a whole heap of things at once then, without looking up all the values for them and adding it all up myself first, I don't know how their offer stacks up compared to the real value, and therefore how much I might want to haggle. Is there a nice little box somewhere that I'm not saying that says something like "vendor is offering you 65% of real value", or even just a real value total printed up somewhere so I can at least compare roughly.

If I'm selling a bunch of swords of varying degrees, a pair of greaves and a couple of shirts, 3 dwemer cogs and come lumps of metal, and the vendor offers me 500 gold, then I need to know if that's a good/bad/terrible offer and it seems at the moment that the only way is for me to grab my calculator, manually go through what I'm trying to sell and add up all the values and then compare it myself.

I'm sure after you've played a while you get an instinctive feel for what things are worth and the sorts of prices people offer you and how far you can push it, but at the moment I'm suffering from severe data drought.

As Nitron noted, the merchant makes an offer based on your mercantile skill, the merchant's mercantile skill AND disposition; you can make a counter-offer using the + and - buttons. Just be aware that the merchant's disposition towards you can drop if you make an offer he/she refuses.

All I can suggest is to chill out about how much of a discount you get. With time and successful sales, your mercantile skill will increase and you will be able to negotiate better prices. If you can, hold off on selling those really pricy items until you've improved your mercantile skill.

There have been several threads on the forums about the bartering system. The consensus is that the mechanics are broken, and there are several mods altering it, each of which explains what the modder thought broken and how their mod fixes it. You can also find discussions about how best to improve your bartering over time.

The offer made on each item should always be proportionally the same when done in one transaction. If you sell a sword, an axe, and a cuirass, they will always offer you the same proportion of their individual values. Its not like they will offer you 50% on the sword, 40% on the axe, and 60% on the cuirass.

And you'll get the best price on low-value items by selling one at a time. Anything worth one gold will get you one gold that way, because there's no fractional currency.

Assuming you're on PC, if you hold down the CTRL key while selecting stacked items to sell, one at a time is moved from your inventory to the vendor. Watch the vendor's offer change as you do this.

The SHIFT key moves a whole stack. Compare the difference in price offered.

With a low Mercantile skill and Personality, you'll be lucky to get more than 1 or 2 percent change in the price by haggling. At the start, try to make total prices add up to 90 Septims or so, and adjust by 1, for a reasonable chance of acceptance. As your skills and Personality Attribute improve, expect to see more significant changes. At high skill levels, you can make serious changes and have them accepted. Since it's percentage based, you don't need to see the individual prices, just the final lump sum, since the markup is the same percentage. Of course, there are rounding errors, so buying two of something together may be cheaper or costlier than buying two seperate ones.

The "broken" mechanic causes the asking price to change as your bargaining ability increases, so half of your haggling gains are lost in just trying to get back to the same starting value. If something had a base price of 50, and the merchant offered you 25 for it at low skill levels, where you might be able to get 26 with a few tries, he'd only offer 20 at a high skill level, but you could bargain that up to 30 or more fairly easily. It's a nuisance thing because you have to do more price adjusting as you improve, instead of less, but not a game breaker.

I believe that problem is fixed by the MCP.

It is. Among the many things fixed by the http://www.tesnexus.com/downloads/file.php?id=19510.