It looks as though Baader do 2″ photometric filters, £171 for the V filter quoted on the FLO website. They are showing out of stock, so you might need to wait for them to order it in, but significantly cheaper than the other options.
https://www.firstlightoptics.com/photometry-filters/baader-ubvri-bessel-photometric-filters.html
I think this has been covered, but unfiltered is definitely preferable to a UVIR blocking filter.
Once you get going, it would be great if you can contribute your observations to the VSS database. I can point you in the direction of different software options to provide the data in one of the upload formats.
Cheers,
Andy (BAAVSS Database Secretary)