Some people use a method to 'swap' from an original game disc to a modified one, by replacing the disc during use, with blocked disc sensors so the console software doesn't notice that the disc was changed. This can then allow a homebrew program file to be started, which in turn can be used to start an FMCB installer.
That is a US v15 slim PS2 manufactured during the first quarter of 2007.SCPH-77001 7A
It is 100% compatible to FMCB, and most other PS2 software.
The method mentioned above can let you install FMCB at no additional cost other than the burned DVD-R discs. But there are some risks in this too, as some disc-swap methods may require you to replace discs while spinning, which puts both the discs and the drive mechanism at risk. (Exactly how the swap must be done depends on the game used.)
And if you don't want to do such swapping, then the cheapest method is to send your PS2 MC to one of the installer volunteers. They charge nothing for the work or the software, so you only pay the postage and packaging costs.
Best regards: dlanor