Don, it would seem to me your client on the box was going to pay the price you were originally asking because it probally would feel akward for them to "haggle" on a price where friendship is involved.
Since you are a part timer, it may be a little difficult to know what your "shop rate" is. When I was a part timer, I was building stuff to sell just so I could buy more lumber and materials. Plus I was using it as an education, you know, trying out different assembly methods, new ways of staining, etc.
Now being a full timer, I figure in my shop overhead, gas for the truck, all the misc supplies (sandpaper, glue, etc), then I kinda do a local survey to see what other door rates are. I also take into account the big box stores (they are competition).
Basicallly down here in central Texas the door rate is $25.00- $35.00 per hour.
So when I bid a job I figure the hours to do the job, materials with a 25 percent markup, and then if delivery is involved I figure gas, etc.
Then I figure a "fudge factor". This could be anything from -
Is there going to be repeat buisiness with this client?
Can I sell them on upgrades? IE: Wine rack, pullout drawers in the pantry, slideouts under the sink Etc.
Or is this customer going to be very picky?
I use this "fudge factor" to raise or lower my bid to compensate for the client.
So I guess the bottom line for me is that there is no set formula for giving an accurate bid.
Cabinet Maker magazine does a yearly bid survey. They take three different size cabinet jobs and ask their readers to submit bids. WOW- you talk about a huge variation in numbers.
All in all, I think you have to price your stuff with a number that you are going to be happy with. And that you think the client is going to be happy with.
Good luck !
Dave