For search advertising:
It depends on the market and how competitive it is. For example, one of our clients in the dating industry is spending over $100 dollars a day, while another in a much less competitive field is doing well spending only around $30 a day. If you have a really tight budget idk say $10 a day? You still will be able to drive traffic to your site, maybe not a lot though depending on the average cpc. Just make sure you find high quality keywords that aren't really competitive. Also if you are on a tight budget like that, make sure you do not use broad match. It will blow through your budget.
Display advertising:
So if you are trying to drive awareness, you are looking at pennies per click. This could be a good option depending on your niche.