You can get Baquacil Oxidizer which is 27% hydrogen peroxide and is stabilized and easier to handle than the 35% concentration. You can get it
here for $14 per gallon or
here for $21 per gallon both of which are less expensive than what you plan to use (even factoring in the concentration difference).
However, since you just want to use this in a hot tub and don't want to use halogens (chlorine, bromine), why don't you use the
Nature2® Spa system which uses silver ions along with non-chlorine shock (MPS) and is EPA-approved for spas so kills bacteria quickly? That's the more common non-halogen system used for spas (the other is Baquacil/biguanide/PHMB). You may still need to use chlorine once in a while every week or two to keep the water clear, but not for every time you soak. Note however that MPS can be irritating for some people, but the silver ions in the Nature2 react with the most irritating minor component in MPS so it's not usually a problem.
There are only four EPA-approved disinfectants for use in spas: chlorine, bromine, Baquacil/biguanide/PHMB and Nature2 with MPS. Hydrogen peroxide is not approved in the U.S. (for commercial/public spas/pools; residential has no regulations except that no unapproved products can make any disinfection claims for pools/spas). When used, it has to be at rather high levels (50 ppm for pools; 100 ppm for spas) for it to be even within the ballpark in disinfecting capability and at this level it can be irritating to the skin. Most disinfectants that are strong oxidizers will be irritating to the skin. Even the Baquacil/biguaide/PHMB disinfectant uses hydrogen peroxide as its oxidizer (though at a lower level) but note that it is not the disinfectant and cannot be used alone in commercial/public pools in the U.S.
By the way, people who use chlorine properly hardly notice the smell. In a residential spa, chlorine users typically start their soak with 1-2 ppm FC and also have 30-40 ppm CYA in the water (via the
Dichlor-then-bleach method) that moderates chlorine's strength by at least a factor of 6 even at high spa temperatures making the active chlorine level far lower than found in tap water. Are you unable to tolerate taking a bath or shower due to the chlorine in your municipal water supply? Do you have a chlorine water filter on your shower or for your entire house? If not, then you aren't as sensitive to proper use of chlorine as you think and instead have just been exposed to improperly managed pools and spas, including many commercial/public ones and residential ones (but not those from people on this forum).
See also
Softtub manual says I have to use their chemicals and
hydrogen peroxide as a sanitizer. Don't say you haven't been warned.
At 220 gallons, would nature2 release toooo much silver? I've never tried it. Also, the product specifies that the hot tub must run four hours a day. Mine automatically circulates the water every 20 minutes, but not for long. Do you think this would be adequate for background sanitation?