AX 2012 - Last cost price

You can put method to InventTable or any table which has ItemId field:

public CostPrice SNBfindLastPrice(DatePhysical _date = systemDateGet(),InventDim _inventdim = null)
{

    InventTrans           inventTrans;
    InventTransOrigin     origin;
    InventDim             inventdim;
    LineAmount            purchprice;
    RecId                 OK = false;
    InventDimParm         dimParm;
    InventDim             dimJoin;


    dimparm.initFromInventDim(_inventdim);

    select firstOnly CostAmountAdjustment,CostAmountPosted,Qty from inventTrans
                order by inventTrans.DateClosed desc,inventTrans.DateFinancial desc
            where inventTrans.ItemId == this.ItemId &&
                  !inventTrans.ReturnInventTransOrigin &&
                 inventTrans.DateClosed != dateNull() &&
                 inventTrans.DateClosed <= _date
        exists join origin
            where origin.RecId == inventTrans.InventTransOrigin &&
                  origin.ReferenceCategory == InventTransType::SummedUp
        #InventDimExistsJoin(inventTrans.InventDimId,dimJoin,_inventdim,dimParm);
    OK = inventTrans.RecId;

    if (!OK)
    {
        select firstOnly CostAmountAdjustment,CostAmountPosted,Qty from inventTrans
                    order by inventTrans.DateFinancial desc
                where inventTrans.ItemId == this.ItemId &&
                      !inventTrans.ReturnInventTransOrigin &&
                      inventTrans.Qty > 0 &&
                      inventTrans.DateFinancial <= _date
            exists join origin
                where origin.RecId == inventTrans.InventTransOrigin &&
                      origin.ReferenceCategory == InventTransType::Purch
            #InventDimExistsJoin(inventTrans.InventDimId,dimJoin,_inventdim,dimParm);
        OK = inventTrans.RecId;
    }
    if (!OK)
    {
        select firstOnly CostAmountAdjustment,CostAmountPosted,Qty from inventTrans
                    order by inventTrans.DateFinancial desc
                where inventTrans.ItemId == this.ItemId &&
                      inventTrans.Qty > 0 &&
                      inventTrans.DateFinancial <= _date
            exists join origin
                where origin.RecId == inventTrans.InventTransOrigin &&
                      origin.ReferenceCategory == InventTransType::SummedUp
            #InventDimExistsJoin(inventTrans.InventDimId,dimJoin,_inventdim,dimParm);
        OK = inventTrans.RecId;
    }
    if (!OK)
    {
        select firstOnly CostAmountAdjustment,CostAmountPosted,Qty from inventTrans
                    order by inventTrans.DateFinancial desc
                where inventTrans.ItemId == this.ItemId &&
                      inventTrans.Qty > 0 &&
                      inventTrans.DateFinancial <= _date
            exists join origin
                where origin.RecId == inventTrans.InventTransOrigin &&
                      ( origin.ReferenceCategory == InventTransType::InventTransaction ||
                        origin.ReferenceCategory == InventTransType::BOMMain)
            #InventDimExistsJoin(inventTrans.InventDimId,dimJoin,_inventdim,dimParm);
    }
    if (inventTrans.Qty != 0)
        return  abs( (inventTrans.CostAmountAdjustment+inventTrans.CostAmountPosted ) / inventTrans.Qty );
    else
        return 0;
}