Unfortunately with today's economy it is hard to get people to open up there wallets to donate to a good cause... sometimes it is because the money is not there.
I too live in a small rural town and this year we are having a quilt show without the usual festival. The festival got canceled because they did not raise enough money last year to host the parade and festival activities this year. They plan to do the festival every other year. A festival or other activities during the event can be a draw... the other organization you are working with might be able to host some family friendly activities... Food usually works out pretty good. My girlfriend's town host a CHILI COOK OFF with their fall festival and it is turning into a big draw for the locals.
Now to address your problem... have you advertised the show so more people can come and maybe increased attendance will increase the money raised.
We do a lot of on line advertising in OUR STATE of MI ... over the years I collected web page links, and posting sites ( local newspapers usually have this but do not be afraid to advertise in all the sites you find for near by towns. ) I post information in the EVENTS section in all the listers in 5 counties.. within 50 mile radius ) I also post in the event calendars that allow community organizations to post a small ad for local activities ie libraries, chamber of commerce sites, real estate offices sometimes have web pages that allow posting. Check out online posting sites your state. The state of MI has a event site to post for the whole state, maybe your state does too. Try googling .... or check your states TRAVEL AND TOURISM web pages...
If you have a state quilt museum ( usually part of a history museum in one of your universities example:
http://www.museum.msu.edu/glqc/onlinenewsletter.html ) they sometime have a web page that will post events on line for you. On line posting is free and you would be surprised how many people visit those sites.
It also will take a long time to post... I usually get started the night the quilt show date is picked. I spend several nights over several weeks posting anywhere I can think of... Be sure to post in all the QUILT related web sites you can find... other people in your state will take note of your show and put it on their calendar. I post on every QUILT RELATED web page that allows posting, most have a posting area for ANNOUNCEMENTS and EVENTS. It is hard work but someone has to do it. This works best if you have your own web page for your event with ALL THE INFORMATION about the event posted on it. YOur web page does not have to be fancy, just factual. If you can't make a web page ... get a kid or grandchild to do it... they can make amazing pages... Get them to post on YOU TUBE and you will be advertising across the world.
example:
http://www.angelfire.com/art3/elainesquiltyshop/QS08.html
You would be surprised how much free advertising is available if you take the time to look for it. All TV and radio stations are required to provide some free advertising for community events, but they get to choose what is note worthy. ( I make a small quilt / wall hanging each year with the logo of the local TV station on it and send it in advertising our quilt show. The TV news team talk about the quilt show all through the local weather, and traffic reports and their community event spots. Last year I got 6 FREE ads because I sent them a nice baby quilt for the newest baby of their one TV staff. Those advertisements alone doubled our attendance last year. OUR quilt show was a bigger draw then the classic car show... that frosted some people's ( chamber of commerce )
butts.)
Be sure to hand out fliers at all the quilt shops and guilds in a 50 mile radius of you town... We mail each quilt shop AND guilds a bunch of flyers and they hand them out.... We do the same for them. Send flyers to nearby community centers, senior citizen complexes... some of them may sponsor a day trip to your event.
Guild members and quilters are your target audience so it is important you take the time to send them information to pass out at the shops and guild meetings. Many of the guilds will post announcements in their guild newsletters. Sometime they will help organize road trips to your event for their members.
I am including some example of sites that might be helpful. The rest of my sites were MI based.
http://www.quiltshops.com/events.htm
http://forums.about.com/n/pfx/forum.aspx?nav=messages&webtag=ab-quilting
I hope this might give you ideas... remember finding free advertisement is hard work but I think it is well worth it. This reminds me I have to get busy for our quilt show... I have a lot of posting to do before SEPTEMBER.