You can repack the iodine crystals in a somewhat smaller bottle, but probably cannot go much below a 1 oz bottle. You need several mL's of solution depending on the temperature of the solution so the volume of the bottle must support the range of volume you anticipate needing.

I used to use 1.5 oz bottles, but find the current bottle somewhat desirable due to the built in mesh screen. This keeps the iodine crystals out of your water.

You pay a fair amount for Polar Pure with the special filter bottle with thermometer. You can probably buy pure USP grade iodine at a local lab supply store and a plain bottle cheaper.

Note: Elemental Iodine is a reagent used by drug makers so trying to buy this has some special implications.

I find the Polar Pure packaging has more advantages than disadvantages so continue to use this.