the best and worst thing about vending at a craft show is that you have absolutely no idea how you'll fare, sales-wise, at the show. i've said many times that signing up to be a vendor at any given craft show is totally gambling. you pay your booth fee, however small or nervewrackingly large that may be, and then you show up that day and hope for the best. because no matter well you've planned for the day - all the work you've put into making amazing products, tagging and packaging each one, devising meticulous displays - you can't control about 5028 other factors that go into whether or not your day will be a success.
generally, my goal is to sell, gross, about 10 times what the booth fee was for whatever show i'm selling at. which is to say that my expectations vary from show to show, of course. how did i arrive at this number - 10 times the booth fee - and do i exist on another planet, with that expectation?
here's my thinking...
when you sell your work through a gallery or boutique, whether on wholesale or consignment terms, the gallery is going to pay you anywhere from 50-70% (typically), and take the remaining as a fee for not only paying for the overhead costs of rent, utilities, marketing for the gallery, etc, but also to provide displays and staff the shop to actually sell your work for you. it's something of a luxury fee for not having to do the selling yourself.
when you sell your work online, you typically pay the venue you're selling through a smaller percentage of your gross. for example, we all know etsy charges 3.5% + $0.20 (or more, depending on how often you renew your items to stay visible in the never ending flow of relistings). let's call it about 5% of your price. then paypal charges another similar fee on the amount paid to you for processing the payment. so, let's round and say that 10% of your price has gone to web fees. this makes sense - they provided you a service of hosting your items while you provided "displays" (in the form of your photos), salesmanship (in the form of the item listing information), and delivery (actually housing the product and getting it to your customer).
in many ways, a craft show is providing a similar service to an online venue, in terms of selling your work to the general public. they have a venue, they do some marketing and advertising, they give you an opportunity to make your wares available to the adoring masses. so 10% is a perfectly reasonably cut to expect to give them of your total sales for the day. which is how i arrived at the magic number that ten times the booth fee is a fair goal.
can a show be worthwhile if you make less than the magic ten times number? absolutely! you can make great connections, form relationships, give shoppers an opportunity to see your work in person (inspiring confidence in future online purchases) and much more. and making 8 times a booth fee (in other words, giving an organizer 12.5% of your gross) isn't such a bad deal, either, of course.
why do i mention this? at a few shows i've done lately (and i've done many already this year), i've heard other vendors mention that they thought a show was "okay" and they'd consider vending at it again, since they made back their table fee. now, let's think about this - if you sign up for a show, and pay a booth fee in advance, and then show up the day of the show to sell and then only sell the amount that you paid for the opportunity to sell there, you've just given away however much the booth cost in products, and much more if you consider your time that went into making the products, schlepping the products there, and sitting there selling (not much) all day. you might be a charitable person, but you would have done better to just pay your booth fee and not even show up, really.