Password Option

The Lanham edi adds some fields to the sales line like "EDI Unit Price" & "EDI Price Discrepancy (Boolean)"

Then it's easy to filter on that field "YES" to see which items are an issue. Then it's up to you to let them go or delete them.

Even easier if you add a menuitem to do the filtering for you. That's what we did.
Caption:"Find EDI Price Discepancy"
PushAction:RunObject
Runobject:Form Sales Lines
RunFormView:SORTING(Document Type,Shelf/Bin No.,No.) ORDER(Ascending) WHERE(Document Type=FILTER(Order),EDI Price Discrepancy=FILTER(Yes))

So if you make it stop with a pop-up message and you have a lot of orders - it's alot of clicking.
This way the orders pass & then all the questionable lines can be viewed at once.

Are you saying you are using Lanham edi? But need a mod to it?

If you are using lanham then you need to look at CU 14000361 - EDI Create Sales Order
There is a section as shown below that will determine that their is a price discrepancy..

SalesLine.VALIDATE(SalesLine.Quantity,LastQty);
IF LastUnitPrice <> 0 THEN
  SalesLine.VALIDATE("Unit Price",LastUnitPrice);
IF LastEDIUnitPrice <> 0 THEN BEGIN
  SalesLine.VALIDATE(SalesLine."EDI Unit Price",LastEDIUnitPrice);
  IF SalesLine."Unit Price" <> SalesLine."EDI Unit Price" THEN
    SalesLine."EDI Price Discrepancy" := TRUE;
END;

Now are you looking to add a dialog message afterward?

If SalesLine."EDI Price Discrepancy" then begin
 if CONFIRM('This order has a Price Discrepancy Item:%1 Price:%2 EdiPrice:%3 Continue?',Salesline."No.",SalesLine."Unit Price",SalesLine."EDI Unit Price", FALSE,TRUE)
 then error('Order Stopped');
end; //not tested just a rough thought.

Personally I like creating the order and viewing the differences after. That requires just training, no code, no mod.

Another way if you create the order is to place code on CU 414 Release Sales Document.
On release it can rifle thru the lines and error on if it hits SalesLine."EDI Price Discrepancy" := TRUE
OnRun()

SalesLine.SETRANGE("Document Type","Document Type");
SalesLine.SETRANGE("Document No.","No.");
SalesLine.SETFILTER("EDI Price Discrepancy",TRUE);
IF SalesLine.FIND('-') THEN
  ERROR('Price Discrepancy Exists On %1 %2',"Document Type","No.");