Need help for concept art project quote

EVF

Hello all,
I just got my first request for concept art commission.
Trying to figure out the price quote part, and usage right, if it applies.
I'l be designing overall views, houses, 1st person view, props...
I'm thinking of charging $35 / hr, but i have a hard time estimating production time.
Should i charge by piece, like, 1 house thumbnails, sketch, turnaround, beauty shot, as one piece for $500 for example (2days work for 1piece).
they will be used for a virtual reality experience and a kinect game experience, what sort of usage right applies there?
Thank you for any ideas 
cheers

Kroma!

Have you checked the Wiki? Lots of info on rates etc.

Eric Chadwick

It's not easy determining rates. I put lots of info on the wiki, but in the end you have to do the legwork to figure it out.

You need experience, and be good about time tracking, to estimate how long it takes to do future things.

You need to know what your monthly expenses are, so you're able to make a living wage.

You need to know what the market will bear, and how to negotiate a deal, so you don't lose work because a client balks at your rate.

In the beginning it's OK to just ballpark it, and be prepared to learn from your mistakes.

EVF

Kroma! yes i did check it right after posting, and i found a lot of good info, thanks
Eric Chadwick i did check your wiki right after posting, thank you for putting all this work into it. 
It indeed helped a lot i was able to figure out somthg fair i think.
For my time management, i will pay more attention to it from now on, i checked the timestamp on my files, and it helped quite a bit.
And i know i wasn't the only person they contacted, so i tried to be quick about my response. No answer back yet, but i'm glad i got to experience the quote thing once, 1 experience notch on my belt
Thanks again