ha ha - ah great! I wasn't thinking of ebay at all!

I've thought about building a tower but wanted to know if its really worth it?
I have a A1200 (with ACA1233) and a NG (Sam460cr) - both giving me what I want but the child in me as considered doing a tower.
I've read though that they can be a little unstable and you really need to know what you're doing.. obviously getting the additional hardware can be tricky and expensive too...
Can I ask would you bother doing it considering what I have or what is it that it gives that's worth the extra effort?
Thanks in advance!