Bags would certainly be less expensive than bottles.
The thing to compare would be bulk prices on small zipper-closure bags versus some kind of bag where you would use a heat (“impulse”) sealer. For my baked goods, I use plastic food bags and a heat sealer ($30 – $50 on Amazon). Of course, you could use something like a Foodsaver or Seal-a-Meal, if you have one, but the added expense isn’t necessary unless you absolutely must have the capacity for vacuum sealing.
For labeling, you could just use address labels and a laser printer (an ink-jet printer would probably run through ink too quickly) and then stick the labels directly to the bags. To be a little more elegant, you could attach a piece of thin cardboard to the top of the bag (if you use staples, don’t puncture the bag below where it is sealed) and then slap a label onto that. Of course, the ultimate would be to have the cardboard tops preprinted, but that would probably raise the cost too much.
Remember: whatever method you choose, the cost of packaging, labeling and any associated equipment must be factored into the price you charge for the item. Otherwise, you could be spending more on preparing the product for sale than you make when you sell it. On the other hand, also remember that the costs of the packaging and labels that are an integral part of displaying your product for sale are deductible inventory (cost of goods sold) expenses.