In New Zealand I believe the upfront cost to PHARMAC (our medical funding body) is about 2250 GBP for a tandem tslim or 4400 for a medtronic 780g (the two pumps currently funded).
But the consumables (cannula etc) aren't cheap either... maybe 750GBP or so per year?
Also, you have the issue that you need support from your hospital clinic with using your pump.... (I've finally got a date for pump training from my hospital, over 3 months after I got my pump, though to be fair I'm happy to lose my place in the queue to pregnant women and children.)