Here are a couple of comments to clarify some of the questions/responses posted earlier. Please keep in mind that I am not a staff member for Swap Meet, and any of this information may differ or can changed at their discretion. Having said that, however, I do speak with the experience of having sold at the last few meets.
While there are a few exceptions (somebody used an example of roller blades last year) as to what is allowed, there is a lot of flexibility when it comes to the items on sale. There have been sellers who come with both current gen and retro video games. Action figures from various sources pop up. Heck, I even sold a Furby from 2001 last year. Cosplay items are usually allowed, but remember that mannequins and other large displays are not. Baseball cards are kind of iffy, but there are always a ton of people selling/trading Magic (and other TCG) cards. Basically, if there's some crossover between what you'd like to sell and the various fandoms held by the average Fanime attendee, you should be in good shape.
I'm not sure if the panel thing has come up before. To be honest, I don't know if you'd want to bother with fliers. They can make a mess if somebody knocks over your stack, and you can be sure Fanime and facility staff aren't going to be very happy about it. Plus, they'll know exactly who to yell at if you're going to be advertising your own panel. Besides, you probably won't have any time to actively hand them out since you'll hopefully be busy selling all your stuff. There shouldn't be any problems with chatting people up for it, though. There's a lot of con and general anime banter going on, so you should have plenty of opportunity to let people know.
Do you need a seller's permit? YES! You absolutely need a seller's permit. It's actually a temporary permit as required by the state of California, and you will need to have this if you want to sell stuff. Don't freak out, though, as this isn't as daunting as it may seem. You will need to print, fill out and sign a single-page form that Swap Meet staff usually have posted as a pdf well in advance. I should have mentioned this earlier, but there will be a page (hopefully posted soon?) on the main Fanime site with all the rules and requirements to participate as a seller. They make it really easy to ensure that you've got everything on the up-and-up. Read and follow everything they post and you shouldn't have a problem.
It's really up to you if you want to have a cash box on hand or not. Like I mentioned before, I'm usually too busy selling stuff, taking the cash and making change to be able to neatly put the money away. I do know, however, that there are some sellers who make use of one and don't seem to have any issues with it. I might suggest having one with you for both transporting any change you'll be bringing (and unless you do have a mobile credit card processor which seemed fairly popular last year, I highly recommend bringing LOTS of small bills) and hopefully the huge stack of cash you're going to be leaving with. You don't want to walk around with potentially hundreds of dollars stuffed in your pockets when the swap meet gets out late at night.
There were some other fairly random thoughts added above (unless I missed something,) but there were some good points that were brought up. Bags - can't give them away in San Jose. At least not plastic bags. If you happen to have a bunch of reusable shopping bags you don't mind giving away, I don't think there's any conflict with the law there. If you bring a bunch of paper bags with you, keep in mind that they need to meet certain regulatory standards - which I won't go into detail here - and you'll be required to charge at least ten cents per bag. I think most people would agree: don't bother bringing paper bags, unless they're for your own use.
Since the con officially begins on a Friday, there aren't quite as many people that show up on Thursday, but there's still plenty of buying/selling to do if you're going to be in the area anyway. The only conditions that I would let affect your decision to sell/not sell on either day are: 1)Are you going to be in San Jose on Thursday, anyway? If so, why not check out swap meet? There are a few sellers who only show up on Thursday, and if you're selling, you may as well try to get rid of some of your stuff so you don't have to haul it all back the next night. 2)Is the seller's fee going to have a big impact on participating? If you can't afford to pay for both nights, then don't. I haven't had any trouble making up the fee with what I sell on either day, so if nothing else, at least it's not a financial burden for me. 3)Do you have enough stuff to sell both nights? If you're lucky you'll sell EVERYTHING you brought on Thursday (has that ever happened for anyone?) and then you'll be able to spend the entirety of Friday night either buying more stuff for yourself or checking out other con stuff. Are you afraid you won't have enough time with just one night to sell everything you plan on bringing? Spread it out over both nights and maybe you'll wind up with better results.
The badge pick up at swap meet was mentioned, but I'm not sure if they've figured out all the logistics required to do it. When they did give it a try, it seemed like an extremely arduous process that, while convenient for the attendees who were also selling, really turned out to be a bigger pain in the side than it was worth. I think it also really slowed down getting sellers processed, forcing the folks at the end of the line to wait even longer. I just mention this so people don't get their hopes up. If someone can figure out a way to pull it off, though, I'd love to see it come back.
tl;dr - If nothing else, be sure to keep your eyes peeled on the Fanime site for news, rules, sign-ups, forms, etc. for the Swap Meet. Most if not all the important information you need will be posted there. In years past, there is also an official swap meet thread that pops up closer to the con where that same information and more specific questions will be addressed by staff. I'm really looking forward to another successful con and meet. Now I just need to make sure I get my name on the seller's list on time. Oh, yeah... that last part - also important.