Suggestion: swap price comparison tool

One of the most common problems with swaps is balancing them. Often the main metric for this is the price of the coins. Unfortunately, there is no convenient tool on Numista to estimate the value of the coins in the swap (for each user). You either have to look at each coin individually or use other websites to value them.

My suggestion: add a tool to the swap page that when you click on a button or link will display a calculator aside from the list of coins, like the one shown in the following sketch.

Description of functionality:
- Each coin will have a coin price for each quality, as listed on the coin page itself for that particular year.
- If there is no stored value for a particular quality, "N/A" will be displayed.
- If a quality is defined for specific coin, then the corresponding price is selected by default.
- The user may click to choose a different price (if it's not N/A), or if he doesn't agree with the price set by other users, he can enter a different price in the "Custom" field.
- The total value of the coins will be automatically calculated at the bottom.

I don't want to discuss in this thread how close the price entered by other users is to the actual price of the coin, as the price of a coin is often subjective. I'm just suggesting an improvement that will make swapping easier for many people.

I agree that this functionality is very desirable. It was implemented by a competing website long time ago, and it was perhaps their most important advantage. 

I think this is a very helpful suggestion but likely impractical due to logistics. The reason I like it is b/c I have had about a dozen collectors ask for a swap when all they have is super cheap dealer stock notes (from former Russian nations which are usually AU) for much tougher UNC notes (mine). I realize a lot of members don't read what a collector wants. So I get the OP notion of balancing a swap since I have yet to have a balanced proposal & I've been a member for nearly 3 years. 

However, I can see several barriers which would immediately sideline such a proposal linking a coin/note's value. Where does Numista retrieve such data on a coin/note? How would the site keep the data current when it continually fluctuates, etc? So many questions unanswered when it comes to applying a BV for any coin/note. Furthermore, the BV is often outdated or not representative of the actual market value of some numismatic items. (Most BV I have seen Numista post on some items are rarely what I paid for my note)

So I am wondering if it would be possible to use another metric.  How about applying the Numista Rarity Index (or NRI) as a helfpul tool? (Or at least notifying the swapper what his or her coin NRI is, etc).  This should be easy to program (with a note that said coin/banknote has a NRI of ___) just so the person who is proposing a trade has a moment to consider (or reconsider) what they have proposed.  It may not change much in curbing unrealistic proposals, but it may help. And it shouldn't be too difficult to implement. 

I like this idea, though not sure how easy it will be to implement. It is always a problem to negotiate large swaps, and it is not clear how the other user values this or that coin. With relatively common it is easy, and I often use Numista values. But sometimes with rarer coins it is hard to do, or Numista values are way off, or there is no grade stated.

So, it will be very helpful to have a feature that allowed to put an estimated value that another swap member also could see at the same time.

Serial_Number_8

So I am wondering if it would be possible to use another metric.  How about applying the Numista Rarity Index (or NRI) as a helfpul tool?

NRI won't work as balancing metric. Simple example, here two coins:

1) N#4787

2) N#3573

Both coins have NRI = 6, however no one will swap these two coins.

Regarding other things that you wrote about: Where data is comming from? How to keep the data current? What about price fluctuates? These are different problems which have different solutions. For example use price data only from latest months, monitor prices on popular marketplaces, etc. However in that thread I want to focus on swap balancing helper and not on where data is coming from (which as I said may be solved by different ways). At the end you may use “Custom” field to specify your price for a particular coin, if you don't agree with the data that is available on Numista.

I would be glad to hear the opinion of Xavier.

By the way, I may implement it myself as third-party userscript, in case Xavier is very busy, but there are 2 problems:

1) Pricing data is not available via API

2) It's hard to fetch issue ID from the swap page