We have been doing Santa Shop for about 10 years, and love it! Lots and lots of work, so my hat goes off to you and your co-chair!
My advice: We use a local company to consign "some" gifts and supplies. We purchase about 75% of our items ourselves, but having the extra items helps relieve our stress levels a lot (what if we don't have enough gifts, what if we don't have enough "guy" items, etc.) We try to sell our stuff first, and the consigned stuff goes back to the company and it's no skin off our backs. As part of doing business with the company, they supply us bags for each gift and also envelopes for each child. The envelopes say "Money Envelope" and have Mother, Father, Sister, Brother, Grandma, Other, etc. with a line next to each. The parents put the amount they want their child to spend next to each family member and the total cash/check inside the envelope.
The children visit the shop by class (we do the schedule), the volunteers can look at the envelope to help the child pick gifts. Once the child has picked a gift, the volunteer puts it in a bag, staples it, writes who the gift is to, and marks on the envelope how much the child spent on that gift. This helps make sure the child doesn't get up to the register and not have enough money, as the volunteers look at each envelope when the bag each gift.
At checkout, all gifts are bundled in a grocery bag, and the money envelope is put inside. Each child receives a small candy cane, which helps them feel like they got something, too!
We sort our tables by Adult Female, Adult Male, Young Girl, Young Boy, Baby/Toddler, Holiday, and $1.00 items. We put the tables in a "U". We only have items on the table for viewing and have the actual goods stocked under the table. We use index cards bent in half with prices marked on them and labeled with item description, which is set next to each item.
We shop year-round, with some of our biggest bargains happening after major holidays: Christmas, after Valentine's Day (lots of stuffed animals), Easter (small games, frames, pastel items, gardening items), Mother's Day, Father's Day (great time to get Dad/Grandpa gifts on sale), July 4th. We talk to store owners/managers and ask that they contact us if they have a lot of items that will be going on sale. We have gotten many items donated this way, also.
Good Dad items: Picture frames, sports trinkets, Sports Team items, camouflage velcro wallets, hand-held games, tools, playing cards, items for car, small photo albums for briefcases, key chains, coin holders.
That's all I can think of at the moment. Good luck and let me know if any of this didn't make sense!