Go to your local college or university chemistry department. They usually have a stockroom, or ask a professor for help. Explain what you need it for.
Ask them to help you buy a 500mL bottle of glacial acetic acid, HPLC grade. This is perfectly clean for food use. Most chemical supply houses accept personal credit cards when the goods are delivered to a laboratory. You might even get a significant discount when it is delivered to an educational institution. The delivery charges will be based on a flat fee, or they might be waived because educational institutions receive regular deliveries by truck.
You want to get a sealed bottle, do not ask for some to be poured from a larger jug. It will come sealed into a plastic bag which you should save for storage at home. When you pour this stuff into your smaller bottle, do it outdoors. Use a plastic funnel and wear the same disposable gloves that you would use for food handling. Wear eye googles with splash shields (the kind sold for painting).
Keep the 500mL bottle in a cool place in a sealed plastic bin. It will last 10 years at least.
Edited by BakingIrene - 1/10/13 at 6:49am