uniopp: Stop!! - I only say this as a "heads-up" to you.
Of course I will be getting an electrician to hook everything up but would like to lay the feeder myself in the meantime prior to deciding which contractor to use.
Do NOT purchase any materials or do any of the work yourself - YET!!
Most if not all licensed electricians will not pick up where you left off due to liability issues.
They will not take the liability for the work you do or for the materials that you provide.
If you are going to do any of the work yourself or buy any of the materials you MUST FIRST be sure that you have a licensed electrician on board with this and who agrees to this.
I would suggest that you call three electricians. Have them come over. Explain what you want done. Let them give you written estimates. Be sure you mention that you want to do some of the grunt work yourself to save money and be sure the electrician agrees to it prior to starting any of the work.
This is a big mistake that many people make.
Let the electrician decide the size of the feeder based on the demands of the equipment you will be running and the future needs of this building.
I highly suggest that you do this first!!