Do you have many details of the type of lamp that you require, such as a picture ?
C7 bulbs are usually understood to be those with a non standard size screw thread, E12 I think, and designed for parallel burning on USA mains so 120 volt. Wattages vary but 5 watts or 7 watts is common. These are readily available from ebay.
Presumably these are not what you require ? Flat topped probably needed ?