you need change this :
<ingredient id="57" count="2000000000" />
Red - here put item id for what you can buy item in your situation is gold bar
Green - here put numbers for how much gold bars you can buy this item
1. if you want add a new block into gm shop go to gameserver --> data --> html --> merchant open your gm shop htm for example 546553.htm
2. if you want sell something for item you must change it in xml files in your gm shop .
because if you have set a complete settings and server are again offline thats mean you dont have external ip only internal for your problem i prefer install program hamachi ofc if your server is for fun .
h4sin without source you cant nothing for example apply patches, fix bugs in core etc .
better find other server pack with source ofc this is my advice .