I wouldn't use plastic buckets for anything with brine or vinegar in it, it might leach out the carcinogenic components of plastic.
Stoneware or ceramic crocks are too expensive, especially if you need several of them because the garden continues to produce over several weeks, but glass jars are your best friend: Anchor Hocking is an American manufacturer of glassware, and it has glass jars up to 2 gallon, you can usually find them in Target stores. You can also find 2.5, 3 or 5 gallon jars easily. Heck, there are even 18 gallon jars from ¢10 to $3 on alibaba.com if you need 50,000 of them!

Now none of the glass jars have the water-tight lid found in ceramic crocks, but you can easily make on yourself: Cut a circle of wood the size of your lid, drill a quarter inch diameter hole in it, form a 8-inch piece of flexible food-grade quarter inch transparent pipe into a loop, with one end going up, the other going down, tape the tube together so it stays as a loop, fill half the loop with water, insert one end of the loop in the wooden lid, and voilà, an airtight lock that lets the fermentation CO2 escape but not the external oxygen in. Use honeybee wax to seal between the tube and the wood, waterproof the underside and side of the lid so the wood does not rot and to keep the lid airtight too, and you're good to go. Chemistry labs and brewers frequently use such airlocks, you can get them on their web sites too. You still need to weigh down the vegetables so they stay under the surface though, there's still oxygen on the surface at the beginning, unless you force it out with a CO2 or nitrogen bottle.

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(5 gallon pickle jar.jpg)

(18 gallon canning jar.jpg)

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2 gallon glass jar.jpg (21KB - 74 downloads)

5 gallon pickle jar.jpg (6KB - 103 downloads)

18 gallon canning jar.jpg (19KB - 87 downloads)

Airlock.jpg (25KB - 74 downloads)