open source: send xlm and receive xml(with extra tag) if test is ok

Dears,

I'm using the open source SOPA UI  to send the following  xml file

<?xml version="1.0" encoding="UTF-8"?>
<pcstore>
<product>
<description lang="en">HP Pavillion</description>
<producer>Hardware Inc.</producer>
<year>2005</year>
<price>29.99</price>
</product>
</pcstore>

I would to return a XML file with a extra tag <pcsupplied>: if price higher than 100.00 , retun message:"To expensive" otherwise :"OK"

In my case:

<pcstore>
   <product>
     <description lang="en">HP Pavillion</description>
     <producer>Hardware Inc.</producer>
   <year>2005</year>
    <price>29.99</price>
</product>

<pcsupplied>To expensive</pcsupplied>
</pcstore>

Can you please help with this, to test it locally, I have soap ui open source 5.1.3 ?

Thanks in advance,

Thié