Mine said $7.00, $14.00 and $21.00. I changed the $21.00 to $5.00 and it worked. So I guess you can decide how much to spend per week and change the third option to that amount.
I tried search ads for one week a short while ago and had no success whatsoever, no significant increase in views and no sales at all. I discontinued before the week was over, so no harm done. I just spent two or three dollars.
I do not particularly like Etsy's proposed key words. I wish I could use my own.