If you have to go down the NEW PUMP route, the Hepolite one is also a consideration, as it has a cast iron body and also here in the UK is slightly cheaper. The big unknown is how well the quality and performance compare in the real world as "new" Hepolite are still a relative newcomer.
But like GB says, although it does cost, the SRM pump certainly has the cachet, and we assume supply and demand are well balanced to maintain the premium price. Funny world when you can get a complex electronic domestic item, say a Smart TV, shipped halfway round the globe for a comparable price to 4 gears, plain spindle 4 bolts, two machined components, flat plate and a drive spindle. Must be the washer and circlip that costs.
Swarfy.