The cheap and nasty ways are to either host it yourself (requires a static IP) or use a shell account.
The expensive and, in most cases - not possible, way is to get an ISP to donate an account and bandwidth for your IRC service. You then need to choose an IRCd, some are free, some cost money but the ones you pay for are more likely to serve you well.
To get the second option you'll likely be a very good 'salesman' or be highly qualified and respected universally.
Bear this in mind: Regardless of your hosting option, it is a popular pastime for lamers and script kiddies to attack IRC servers in one way or another, usually by choking the connection with warbots. If you are charged for the bandwidth you use or you have a bandwidth limit or you arn't savvy with security and server defence then don't be in a hurry to run an IRC server.