How much to charge?

So, the place I work had me build two PC's for the drafters/machine programmers to use.

When I got finished, the computers ended up being a little less than $1000. My boss told me to keep track of how long I spent on them, and when I went to tell him how long I'd worked on them outside of work, he told me to just bill him.

How much do people usually charge for building PC's for people? How much should I charge for these two machines? I want to be fair, but my company is very very wealthy, and I really could use the money as I'll be starting school full time this Spring. What do you guys think is a fair price for the actual labor involved in building them?

My PC has a totally cost abou 700€, so it's about 930$, I guess much cheaper and you can throw them allready away if paid.
I recommend you a NVIDIA Graphiccard and a INTEL processor. Because ATI overheat easy and are not really good for overclocking.
The AMD processors are only good, if you use them most time for work, because they are faster under Windows, but if you want to game more, then you should defenetivly buy a INTEL. (\s/)

Find some prebuilts with similar specs and charge a little less than what they're priced at. I bet you could get away with 1,200$ each though.

They're already built, I just need to tell my boss how much he owes me in labor.

How many hours did you clock in? If he's rich charge $20-$35 an hour depending on how comfortable you are. I imagine it took roughly 10 hours, so 200-350 in labor plus parts and include your transport costs to work each day, gas or transit on top of that. Add %15 taxes and send him an invoice, which should be a pre-loaded template on Excel.

Is it really necessary to charge tax? Sounds great, but is it necessary? The computers ended up being about $1200 each. The company I work for is very wealthy. The owner just got a $3 million deal for storing a neighboring company's junk in our extra warehouse for 3 months.

I'm trying to get a (don't judge me) Surface Pro for school in the fall. And that'll run me quite a bit of money. I was hoping that I could pretty much just have them buy me one. But that's too steep of a trade off in my opinion, so I'm going to ask for money to put towards a Surface Pro.