Using an AS/400 for a high volume on line store

HI I met the owner of an online store. They currently use Yahoo as their store 
hoster. She said that they would like to switch to inhouse but think it would 
cost 250K. They have about 15,000 items and are doing about 3000 orders a week. 
They are experiencing increased growth. They have an affiliate program no 
online customer service. Many orders have to be faxed in anyway because they 
may have an 'as is'  status and have to have a signature. I just want to know 
if an AS/400 and which one could be their hardware and what software or 
utilities would be needed, and would the price be much lower than 250K? I 
realize this is very general dimensions but I can find out more. Obviously 
because I am familiar with the 400, I want to offer that I can help facilitate 
the transition.    


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