Snoopy,
Why not call the electrician and ask him what the savings would be if you supply the parts did the trenching so all he needs to do is run the lines and the actual hook up.
Decide where you want the spa. Then pick the area of the spa that you would want the wire to go in. Some people put it in the bottom I had mine go in the bottom right hand side. The disconnect needs to be 15 feet from the spa. Dig a trench from the spa to where the disconnect is and to a place in your home where it will go in to the electric? Do you have a basement? Is it finished?
In my case I ran the line into the side of the house and routed the wire in my basement to the electric box. The disconnect attached to the side of my home.
Also realize the wire itself is very expensive.
your electrician may buy in bulk or wholesale but he is making a markup on you. Also maybe ask him to break out the prices for the parts.
Is this a new tub? I just hooked mine up this spring and with moving it electric, cchemicals, cover lifter etc etc my free tub cost me about $2,000