There once was a fencer named Sarah,
Who posted in the 2003 era.
She asked this question online,
and got a hard time... ... ...
Jeez, this last rhyme's a terror.
http://www.fencing101.com/vb/showthread.php?t=6373
There are some sponsorship hints sprinkled thru the postings in the linked thread. It's not the easiest undertaking but you may be able to hook a few sponsors. Your needs are modest compared to some athletes, so it may be in your reach.
Your best bet is to tap an existing community, to which you belong. Club or church or your special ed class... these are the people who will generate your money. Now, hit up friends for some stuff (old sports equipment, clothes, silver platters). Visit businesses, get more stuff -- vouchers, coupons, freebies (you might even get some cash). Then you could hold a blind auction and have people bid, or hold a raffle and get ticket sales for the item(s). Merely selling the items (at a swap meet) won't generate much money, as I found out once in your situation.
For example, at a blind auction for the Humane Society, my wife once bought a free meal at a good local restaurant. She paid $80, but the meal was worth $150+. The restaurant got a write-off, the HS got $80, and we got some food. Blind auctions need a lot of people filtering through, writing their bids sequentially on a slip of paper, usually while they're doing something else (so at a church event or something).
If you have the time to organize, you can tie YOUR needs to something else. Appeal to a church organization by having a "Send Joe to Nats and Help The Needy" auction/raffle -- whereby, half the proceeds of your hard work go to a charity, or the church. This will allow you to use the promotional, locational, staff, and time resources of the church (or other), stuff you wouldn't get if you held a wholly self-motivated raffle.
Other, harder ideas (also stolen from charity events) -- a dinner for $20/plate, or a beer bash for $10 at the door, or a special "Kid's Class" of 2 hours of learning about fencing for $10/kid (be sure to mention it's for a Cause). For this last -- show videos, pass around a sword, talk about the history of fencing, play fencing games... have stuff prepared.
If you're going to be the focus of the event, then you need to entertain people somehow -- sing a song, or give a motivational speech -- to pitch your needs and get people to contribute when the hat is passed.