Cheap and easy to find alternatives to ONA ?

Anyone build an ONA bucket and find a good cheap locally available alternative to the ONA? Something at walmart or home depot? Or is ONA still the best? I bought a few gallons years ago and have ran out now.

These natural magic odor absorbing gels are about $4 at home depot. They last about 2-3 months as is. I drilled holes into the sides and glued a computer fan to the top. If I run it constantly it smells too strong, so I only run it when needed around the house. With constant use it lasts maybe a month, part time use they last 2 months.

The other picture is my ONA bucket. It has a computer fan attached to the top. The inside is filled with soil moist crystals, water, and ONA. It runs constantly and covers almost any smell.

I picked up some ZorbX and it works ok in the bucket. It really has no smell at all. It lessens the bad smells but doesn't completely get rid of it. If you don't want it obvious you are trying to mask a smell it would be ok.