Having a C Corp is necessary only if you are seeking _venture_ funding. Other funding, like angels, friends+family, etc is available to just about all types of corporate structure, depending on the skill of your lawyer in setting up the investment structure.

Most businesses won't ever get venture funding, so setting up a C Corp now "just in case" is typically a big waste of money and effort. Instead, used some other entity type, then if you really need to, convert to a C Corp. Your early $ are far better spent marketing your product than on lawyers for corporate formation activities.