Just buy them online and fit them yourself (easy job with basic tools) or get a local garage 2/3 hours labour.
Don't be scared, if you've fitted discs and pads before to any car you can do these.
Just buy for example front and rear Alcon's and ferodo ds2500 for road use. Can or two of brake cleaner,copper slip for the calliper bolts and wurth do a brake pad lubricant.
There's a few vendors on here so give them a try for quotes.
ACspeedtech in Bolton?
Middlehurst and R B motorsport in that neck of the woods also
Discs and pads all round are a couple grand? few hours fitting, might not be that far off the Nissan price once you put in time and petrol?
You will get better brakes though to be fair.
I'm thinking AP/Alcon J hook discs with standard or road use pads maybe not DS2500I had AP racing j hooks and DS2500 pads fitted all around that money. The pads have no feel compared to the OE pads. A friend of mine had the more track biased pads fitted and says the feel is far superior but Frerrodo say these are for track use only. The 2500 stop you ok but the initial feel is soft and crap imo. However everybody to their own.
I would not replace discs with oe as the crack from the vent holes. I changed mine at 4k miles due to cracks. GTRDC have got a make which they bring to track days and look ok and the right price. Speak to John who has developed these. Pete