When the Professor's daughter asked if I would host a spa slumber party for her 8th birthday party, I was happy to oblige. I have a tendency to over-plan, over-spend and generally over-do things like this, but this time I decided I was going to exercise restraint and try to make it fabulous on the cheap. In searching through Pinterest, I was surprised at how few parties like this were pinned. Most of what I found online was geared towards hiring someone who brings everything in for you and…