Why are you going through the cache? This is a forum for mainly Server Developers, If you are a developer, why not just go through your database? And there's no repping here the last time I checked.
[Writing this guide out for Wotlk 3.3.5a Guide]
Otherwise, use an addon that shows the ItemID of an item you may have equipped, Such as Rating Buster(will need to toggle ItemID through the Interface Settings ingame).
And you'll get something like this:
Now we see tha the ID is 78487
Now you need to close out your game and go into your Cache folder, then WDB, then your region folder(mines is enUS), Find the itemcache.wdb file. Move this file to a new folder.
Download
WoWParser2 and extract it's data to the folder where you put the itemcache.wdb folder.
Here are my files in a folder.
Now Open up the WoWParserReader.cfg file in a text editor like Notepad and add a line somewhere that says *.wdb and at the bottom where it says:
#itemcache.wdb iiissssiiiiiiiiiiiiiiiiiiiiixnnnnnnnnnnnnnnnnnnnniiffiffiiiiiiiiiifiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiisiiiiiiiiiiiiiiiiiiiiiiiiifiii
Remove the # so it's just
itemcache.wdb iiissssiiiiiiiiiiiiiiiiiiiiixnnnnnnnnnnnnnnnnnnnniiffiffiiiiiiiiiifiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiisiiiiiiiiiiiiiiiiiiiiiiiiifiii
Save it and close it out, now run the WoWParser2_ADB_DB2_WDB_DBC_Reader.exe file and it should output a file called itemcache.wdb.csv , Now drop that file into a text editor and you'll get something like this:
Now my number was 78487, so I look for that and find the name. Then 4 commas after the name is the Display ID, in this case it's 102679.
I Used Notepad++ as my text editor.