Compared to anhydrous ethanol with about 100 US\$/L -everclear seems to be a very nice and cheap substitute (30 US\$/L). It is perfectly safe to drink diluted so the remaining stuff should be almost only water. (Almost undetectable) Trace amounts of essential oils might be present, but as it is made from grain, very unlikely.
Anhydrous Magnesium Sulphate is about 6 US\$ for a quarter pound (about 110 g) and you might need to add all of it. As LDC3 already mentioned you might solve some of it, not sure if you want that.
Coffee is also kind of expensive and in my humble opinion far too precious to use as a filter. Yet again you will solve some of its contents in your solution. (In response to LCD3's comment)
If you use your potions for outside application only, you could try and search for perfume base alcohol, which could be a little cheaper. It is denatured, so it is absolutely not safe to drink it. There is also industrial cleaning alcohol on the market - but here again you cannot be sure what exactly is in there. It is very hard and expensive to get rid of the additives in denatured alcohol.
The main price of alcohol comes from taxes anyway. If it is intended for drinking, the in most countries spirits are heavily taxed (luxury goods). Working around that is no good idea. When it comes to your own safety and your potions users, do not by too cheap - consequences could be far more expensive.