Personally, i dont think you should start as high as 20-35 dollars. Ask yourself how long it took for you to get the sounds you got from that recording i heard. If it took you hours and much trial and error to get some of those then you are not ready to record professionally. Recording someone else is a totally different thing, and charging that high could cause some serious problems. Being unexperienced can cause you to have problems with some of the things and somebody who is paying that much for hour will not want to put up with anything. However, $10 an hour starting out is definately not unreasonable, and if you end up having a few glitches or stability problems they wont have alot of room to complain being at only $10 an hour. If there are problems, in the end they will be satisfied because they only paid $10 an hour. You need to remember that the main thing is to make your clients happy, make sure you give them what they want until you get alot of trust. After the trust and a little more experience with working with other people, then you can start to raise it. Most of the pricing with things is based on your clients trust. One reason why the top engineers can charge $200 an hour for their recordings is because the client KNOWS for sure they will get a good recording.
Danny