It's denatured alcohol,same exact stuff you get at home Depot. It just has some glade or febreeze oils added to it. Hunters can be sold anything. Just look at energy drinks,add some camo to the can and bam ,you upsell and cater towards hunters. Or add some camouflage realtree camo to Crocs and charge 10 bucks more. A quart of dentatured alcohol is 7 bucks at Walmart you might need two for most applications.
If I ever got into the scam market I will package baking soda into a spray and call it scent killer spray. Or just rebottle some water and pinesol mixture and sell it as mount cleaner.
How you preserve the velvet is determined by the state and age of the rack ,if it's bulbous and bloody and fleshy ,it must be freeze dried. If it's sort of fleshy and bulbous but also sort of hard underneath ,it can be injected with alcohol and bit of formaldehyde or formalin,if it's hard velvet it's fine to just dry on. The velvet you see sometimes in October whitetails,the strips of it that sort of peels off like a bandaid . And in some cases the velvet gets stripped off the bone if it's in the half way or 3/4 state and then replaced with artificial velvet