I have a reference I can give you and I've been working with them since November 2010. The way I usually work is I separate the 'project' into smaller sections and then charge per section based on how long they take. So for example if someone wanted an arcade project with a handful of PHP run arcade games, I'd separate the project into the main arcade page and then each game and charge individually. Also, if a single mod will take me more than 8-10 hours(about $100) then I request a $20 upfront payment. It's not really required but it makes me feel more comfortable so I'm not worried about doing this huge mod and not getting paid. Up front I'll give you an estimate as to how long the mod will take for me to code in straight hours. If I go over that I don't charge more, but if I go under I don't charge as much so I make my estimates as accurately as possible. I am in school so I request a little bit of leniency around exam times (Middle of January & end of May). If there's anything else that I think of I'll let you know, but yeah PM me if you're interested.
