The cheapest and easiest route is Tanner moulds. They are across the pond but the Pound/dollar thing is no problem. The molds don’t have a sprue cutter, but the design almost guarantees a void free ball.
More conventional Lyman/Lee style molds are made in the US by Moose moulds and Tennessee Molds. These are a lot more expensive and neither, the last time I looked, do online ordering.
All three will make any diameter you want.
I only have experience with Tanner, but both Moose moulds and Tennessee molds seem to have a loyal fan base.