My apologies, I changed the selection country from England's to Germany and had to make some changes, your quite right the prices are expensive for ram and ssd systems.. here is a revised , so 8GB ram, only 250GB drive but remains M.2 port, and a great little dual 5.GHz Wifi card 1180 euros
The price are more to give you an indication what "more": you could be getting.
yes you pay for built and service when you get prebuilt.
PCPartPicker part list /
Price breakdown by merchant
CPU: Intel - Core i5-8400 2.8GHz 6-Core Processor (€169.90 @ Caseking)
Motherboard: MSI - B360M GAMING PLUS Micro ATX LGA1151 Motherboard (€87.59 @ Alza)
Memory: G.Skill - Ripjaws V Series 8GB (2 x 4GB) DDR4-2666 Memory (€98.00 @ Amazon Deutschland)
Storage: Samsung - 860 Evo 250GB M.2-2280 Solid State Drive (€69.89 @ Amazon Deutschland)
Storage: Western Digital - Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive (€39.95 @ Amazon Deutschland)
Video Card: Palit - GeForce GTX 1070 8GB Dual Video Card (€445.14 @ Amazon Deutschland)
Case: Fractal Design - Focus G (Black) ATX Mid Tower Case (€50.98 @ Alternate)
Power Supply: SeaSonic - FOCUS Plus Gold 550W 80+ Gold Certified Fully-Modular ATX Power Supply (€80.89 @ Alternate)
Operating System: Microsoft - Windows 10 Home OEM 64-bit (€94.93 @ Mindfactory)
Wireless Network Adapter: TP-Link - TL-WDN4800 PCI-Express x1 802.11a/b/g/n Wi-Fi Adapter (€43.59 @ Alza)
Total: €1180.86
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2018-06-14 15:41 CEST+0200
I am looking at Denmark web sites that build system for people but all prices are in Danish Krone so 1000 euro for 7500 Krones I found nothing even close to the price your got quoted .. nice job btw. (Danish web site average 12,000 kr for similar system you got quoted)