Can I/ Should I switch to T5's?


I will try to ask intelligent questions, but honestly don't understand lighting very well.
Currently I have a Hamilton 2x175 MH with 2x55CF. I believe they are about 3-4 years old. (WE bought it used about 2 years ago. )The CF completely stopped working. So My husband tested them, said the ballast is bad and needs replaced. Also tested the dual MHs. They currently work but are not running equally. So we assume that ballast needs replaced also.
I have to be missing something, because I can't undertand that more than half of the cost of this unit it for the hood. I assumed that the replacement ballasts would be more expensive. According to their site this is a $600+ lighting system. Yet the ballasts only cost about $250 total. I assumed that we had some sort of homemade hood but it looks like the one on Hamilton's web site. I don't understand why the lights as a whole unit cost so much. What am I missing. It can't cost that much to fabricate a hood and add a few sockets can it?
Really don't mean to sound like a smart...! It is probably just my ignorance.
Anyhow, it it possible to switch the CF over to T5's? Is that a better choice? What are the benefit of one over another?