A number of private collectors who collect antique bottles and jars have websites that list parts of their collection for sale. People can also shop for old glass bottles and jars on eBay.com.
In most circumstances, what a private collector offers for sale changes with what's in her personal collection. A list of several private collectors can be found on AntiqueBottles.com, though prices and shipping can vary a great deal between people.
EBay.com offers more security, in that the company oversees the transactions. However, as with private collectors, the items for sale can change a great deal from day to day.