Ya, depending on the terms and such, $40 - $75 sounds about right. Keep in mind that you technically need to be paying income tax on this money, insurance for yourself if you are a contractor, etc. Local cost of living is also a big factor. So if you are 100% legit, you will likely want to charge more. If it's a cash only deal, then maybe charge on the lower end. You should talk it over with the client though, just so they know where you stand on the whole money issue.