Thanks, everyone, for the replies and suggestions.
I think that the show was a success for her primarily because of three items:
1) She had to plan a reproducible craft that would appeal to the low $ per item market. In the past, she has only sold one of a kind items, at art gallery type shows or commissions. (Has sold only 4x this way, but it is a start). It takes a different mindset to take one idea, make three versions of it, and then create 10 of each with variations. She also had to buckle down into "production" mode, which is new.. and now has "leftovers" to consider.
2) She had to take costs and fees and net out proceeds. Business math, as many here point out, is a failing of many vendors, so this was crucial early in her "career".
3) She had to coordinate a booth with another vendor. (Her share of the booth was only $7.50, and the other vendor waived that because DD did the legwork to acquire the table when the others sold out). This was a fundraiser, for crafters only, and the main draw was the huge bakesale and raffle going on upstairs at the same time, that attracts up to 200 people each year, who line up while waiting for doors to open.
4) Learning that the least expensive, least artistic item on her display was the one most in demand. (a laser cut, custom designed steel snowflake). If she had cut out the copper metal items with their custom painting, and emphasized more laser cut designs, her expenses would have been half.
5) Time management - she was stressed before the show, not used to a deadline for producing more than a single item and could not spend the time she wanted on each and every one. Also the somewhat boring aspects of sitting at a booth for 5 hours... nicely filled by working on the crafts at the booth, which was when she sold the most...
6) Show prep - planning a display, a money float, getting a credit card reader, (YES! she took credit cards!), posting prices, etc. DH and I essentially did these items for her by asking questions, doing it, handing it to her, etc. But learning for next time.
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From your replies, I tend to agree about how to be successful with craft fairs... the most successful people:
1) Sell through a gallery (with high overhead to the gallery or a online site) and direct from their studio (as commissions), first.
2) Choose one or two fairs per year, and produce all year for that fair. One vendor I know chooses the Vancouver fair at the convention center around this time of year, with its very high entry prices, but produces wooden high end items from their studio near Mabel lake, BC. They have ONE fair where they make more than half of their income each year, and the rest is from their studio / gallery per point 1 above.
3) Material costs - use of found materials -- excellent idea! Especially for metal works for art, there is such an abundance of scrap metal from industry production runs. We are also quite close to many metal recycle shops where we live.
4) This one is not mentioned, but I am starting to do it for my work conferences -- advertise to your clients ahead of time that you will be at XX fair.. to drive people to the fair specifically to see your display.
5) The comment about choosing a fair that does not have the MLM vendors, and have similar theme or concept is a good one. I also noted that there are "textile / quilting" type fairs and "artistic" fairs (which may have hand crafted textiles, but with a unique approach)... or a theme fair such as Christmas, steam punk, etc may be better, with targeted theme items. -- I think that the local maker fair that she and DH attend each year may be a good location for her metal crafts, if the price is low enough to enter...