I still think building that Meta42 is the best thing you can do... here's why:
#1, You'll get to spend some bonding time with your dad doing something that's inheriently testosterone driven. It may not sound like a great thing now but...
#2, You will both come to understand each other. You will understand why he thinks it's insane to spend money on audio and he may just come around and understand the enjoyment you get out of it.
#3, If he likes what he hears you may just drag him into this hobby with you! And with that a life-long close relationship might just deveop all because he said 'no' to spending a few hundred on an amp.
#4, You will likly end up with an amp you will be MUCH happier with in the end! It will be built to *your* specs for *your* equipment with *your* hands. You can't say that about an Orpheus even!! This amp will inheriently be *yours* and is a product of creation through both your's and your fathers hands and minds. There is no amount of money you can put on that.
#5, Both you and your dad will learn something from this venture. Even if it's just each-others limits.
At your age, lets face it, you have more time than money. This really is the best option for you. I'm also sure that's what your father sees as well though he may not have phrased it in a way you really wanted to hear.
After going through this experience you may find he is more open to you spending some cash on a pre-built amp. But, if you do it right, you probably won't have that craving for a while. Instead you may be trying to talk him into letting you buy a $8000 Wadia 861 (try doing *that* yourself!).