I got started building engines after getting screwed over by a shop on the first 440 I put in my cuda in 1998. After that, it was all me b/c I wanted to know exactly what I was getting. It's too easy for someone to give you a completely built engine and lie about what's in it.

I never understood why someone tells you a week and then it ends up being 2 months for no apparent reason.
I ran a small machine shop for about 6 years and loved doing it. Always stuck to the price quoted and stuck w/ the time frame religiously. If it had to be adjusted, I let the customer know ahead of time. Always treated people like I wanted to be treated b/c I knew all too well how bad it is to be screwed around w/ on an expensive and important piece of your pride and joy. We didn't assemble engines there for liability reasons, but I'd do them at home on my own time.
I found out real quick how expensive the equipment is and how cheap customers are...especially in this area. When you have a $45k head surfacing machine (cheaper floor demo model), charge $30-$50 per head, and people complain about that...it gets frustrating.
Had to send cranks out to 2 other shops to get turned b/c we didn't have a crank grinder. Talk about an expensive piece of equipment right there.

Most of our bread and butter was rebuilding stock heads off anything and everything for local garages and dealerships. A lot of newer stuff can't be rebuilt, it's all just replaced w/ new. Pretty soon all of your business will be people rebuilding older vehicles and, of course, race engines. Here there isn't enough of either to keep a shop going (10-15 years ago anyway), so I went back to school and changed careers. The shop I was at closed 6 months after I left. Of course now there are more and more shops closing so it would seem a GOOD shop could do pretty well. I'll run into some of my old customers and they'll ask when I'm gonna open my own shop. I say as soon as I win the lottery and have money to burn. Even had a fellow racer and business owner offer to buy the equipment and set up a shop for me to run, but that never worked out.
There are only 2 good local shops around here now and I'm fortunate to be friends w/ them. My stuff usually gets done quick and I try hard not to be the nightmare customer that used to do that kind of work.
I have bought stuff here and there so I only have to have minimal work sent to the machine shop. The best thing is to have your own dial bore gauge and micrometers so you can check what your shop machined for you.