They tend to be a reliable source for quarts and gallons. I have the same problem with them that I have with paint stores, home depot, and lowes who also stock quarts and gallons of alcohol. I much prefer to carry way less than a quart at a time. For me the 12 ounce bottle of Yellow Heet is about what I usually want to carry on a road tour since my perference is to travel very light and restock often. I might resort to carrying more if cooking for more than one person or in an area where I will be unable to resupply frequently, but in those cases I have tended to use a different stove rather than my alcohol stove. So when buying at home a gallon or quart are fine, but on the road I'd typically rather pick up a 12 ounce Yellow Heet.

On a different note:
These days I have been getting away from alcohol stoves more of the time for backpacking due to the likelyhood of fire bans requiring a stove with a shutoff valve. I also have tended towards other stoves for canoe camping lately. That had meant canister stoves, but I have been tending more toward white gas stoves for those uses. I had a similar issue to my problem with alcohol fuel and wanting to buy small quantities of white gas, but solved that when I realized that zippo and ronson cigarette lighter fluid was naptha (not the same stuff as charcoal lighter fluid which is more like kerosene). I find that I can buy it in a variety of sizes (4, 5, 6, 8, or 12 ounces). Prices for the naptha lighter fluid can vary pretty widely and it is quite a bit more expensive than buying a gallon, but I have generally found it for something that I didn't mind paying given the convenience of the small size. My local Walmat has 8 ounces in stock for $2.19. My local Walgreens has 12 ounces for $5,79. The local Ace Hardware has the 5 ounce for $2.99. Obviously it makes sense to buy a gallon when using white gas and filling the fuel bottle from at home. I can get a gallon of the Coleman stuff locally for $14.47 and the Crown brand is available locally for $7.64.