I noticed while browsing ebay that asic chips are for sale, just bare chips. 

I was wondering if it is possible or economical for someone to buy these chips and try to put together their own miner.  I was thinking you buy a PCB and put the chips on them then just supply power and some sort of controller?  Why would they sell just bare chips?

I am really over simplifying it, but I am curious as to if this is a possibility, because it seems like it would be fun to do.

Where / how do you find a pcb to put these chip on?  Is it difficult?

Are there any people that build their own DIY miners using these parts?