This year was unusual regarding size. We changed venues, had it at a church hall and were able to increase the number of attendees substantially. In years prior, we would have about 300 attend. We always sell out and have people on wait lists for tickets. Our township is large with 6 grammar schools that all run auctions, so competition for donations is fierce.
We do a mass mailing in the fall and in January start following it up with phone calls. I coordinate the solicitors so I can tell you that it's a huge, huge, HUGE amount of work amassing the donations. We work it like this: We put like items together to form baskets, they are all themed and named. We define catagories of baskets using color: white for baskets that are worth under $75, purple for baskets worth between $76 and $200, yellow for grand prizes and red for classroom baskets. Each type of basket has a different ticket price, all tickets are sold in sheets and all coordinate. Table cloth, ribbon, ticket, labels, bags all will be either white, purple, yellow or red.
This year we had 146 white baskets, 182 purple, 34 grand and 24 classroom. We started calling at 8:30 (should have started at 8 pm but got a late start) and the evening finished at 11 pm.
It's good that you have the volunteering hours requirement. That should help you. You need to encourage people to volunteer their time and NOT keep track of their hours. The last thing you need is for someone to get half way done with a function and then say, 'That's it, my 50 hours are up, I'm outta here'. I literally spend hundreds of hours on our auction this year, on top of working full time.
If I were you, I would have a start up meeting in the fall to get your different sub committees lined up. You need to know how many people you can count on. I would also look for a co-chair, someone you can count on, bounce ideas off of, share the stress and alike. It helps.