here my 2pence worth,

DIY builds are ok but you will make errors and must be prepared to spend a bit of money just cause its DIY dosnt mean its cheap!!

why do you think there are specialists around if they are so easy to build??

if you are building a completley standard build then i dont see a problem with DIY but as long as you are competent, i have seen so many DIY builds that are just shite and the owner thinks they are brilliant, hoses diconnected/parts not put back on/rounded off bolts etc...

another hard thing to do is finding a machine shop that you trust, not as easy as it sounds!!

a specialist will have made these contacts/equipment already, you will have to start from stratch.

good luck with your build matey