For small baits I generally sell them in packs of 10 of one color and use 2X3 zip locks. I add a couple drops of worm oil to each bag so the baits slide easily. I'm not concerned with their being straight in the bag. Walleye sized split tailed baits and fluke-like baits I sell in 10s too but will take time to be sure they are not bent of folded over in the 2X3 zip lock bags. I ship most baits in bubble mailers and will put the zip locks in appropriate sized laminated bags to prevent oil seepage, then in the mailer. Larger baits, larger orders, and orders including a lot of jigs go in a small, flat-rate, priority mailing box. I bag baits for sale in 10's, one color. Oiling senkos/worms in a cake pan and using a pancake flipper to slide them in the bags can help cut down on frustrations related to bagging, but the oil also creates its share of frustration. Packaging techniques are really those things you have to try to see what fits for you.
Senkos and worms I think are the hardest to keep straight in bags and probably should get some cure time to help prevent bent products getting to the customer. Cure times are really varied.... for some people a couple days is plenty but for others thick baits may cure for a couple weeks or more. Myself I make small baits and inject them , lay them out on a cookie sheet the way I want them to look and let them rest overnight. Then its in the bag and in the mail...or in my tackle pail. Those being mailed get the oil, personal stock goes right in a plano and they see no oil.
I use U-line a lot for zip locks. I can get a thousand 2X3 for 13.00 bucks or so. 2X3 slightly more. If you do high volume sales and shipping, the bubble mailers and other bags and laminated bags are very reasonable at U-Line. I think Do-It gets a lot of their packaging from U-line. The flat rate priority mailers you can get free from the usps. Go on-line to their site and snoop around and you can find the freebies. I like the set rate...saves a bunch on farting around trying to get shipping estimates plus you're insured to a certain point and get a tracking code. The usps may also have free bubble mailers now but I'm not positive on that.