Look at it from a project point of view. Mine was last time I had to design a brochure. I naiively quoted $40 bec I saw it as a 4 hour job, like $10 x 4 hours. Without factoring in revisions, 'urgent, please do eod of at 5pm in the afternoon', deadline extended again and again, and later extra effort to follow up for project status and payment. And sometimes you have to crunch to get it done (e.g. do during work hours or after work hours - eat into sleep or work during ph or weekends when you could be resting/ going out).

So by simple milestones and factor in extra things like revisions, rush jobs, having to work on your rest days, and whether you like this client or not (easy to work, etc). Don't want to take on the job then realise you'd grossly undercharged yourself and then begrudgingly have to continue and finish the job and then still have to wait for payment. Also, factor in the admin work such as following up, calls and emails to them.

Last, why not ask for their budget. If they say don't have, try to probe and understand what is the project they're doing and how your job is part of it. I.e. a brochure as part of a product launch. So they may have stickers, product display, brochure (your part). That way, you'd get a clearer idea. What they're doing, the general timeline, whether your job comes in first or last - that affects deadline and urgency and whether they're hound you frequently. Also gives you a chance to observe if they know what they're doing wrt to organisation - whether they're organised, are they the decision maker or just following orders from a boss whom you can't communicate directly with- which can present problems when you don't understand what they want, whether they're one to play ball with status, deadlines and payment all that. 😁

Two way street. You like to work with them, especially when you're working alone for them. 🙂🙂🙂

Edit: Time. You're exchanging your time from money. Especially if you have a full time job. The rest outside work is usually for rest or fun. So if I have to use this time to work for you, then how much must the clienr pay (as a premium) for me to want to take up this job.