Sarah,
I always request an "outline" or "plan of action" before you start giving out your services. I typically don't like to barter unless it is stuff I really need. Currently, I only barter with my massage therapist. I train her, she massages me. She knows me, I know her. Period. New clients...I never trust their bargaining and ALWAYS make them pay up front. Subsequent sessions may be up for barter if I feel they are trustworthy and I actually "need" them.
For instance, I have joint ventures online that want, want, want...but I ask them to give me an "outline" of their product before I actually put in the time and effort for a contribution. When I see the "framing" of a product or trade-off, then I start the effort.
You should contact this lady and hit her up for the $400. If you wait any longer, your argument will lose steam (if it hasn't already
