He might be more inclined to help if he could see how much moolah he could save by building it for you. My hubby doesn't like to do carpentry things but he would balk at my spending that much for a sewing table. It could be really simple and still do the job.
Another idea, maybe you have a friend who is handy at building things who might be willing to swap his skills for something that you or your husband are handy at...maybe you could make a quilt for him/her or do some cooking, etc. I'm very frugal and would have a problem spending that much but that's just me.