That's a very handy website. We occasionally get German people who want parts recommendations and PCPartPicker does not have a very expansive price database for German retailers, so I'll be bookmarking that site. Now for your parts build..
The non-overclocking i5 4460 processor is compatible, but is not the best fit for a Z97 overclockable motherboard. Ideally you'll want to get a K model overclockable processor to match the Z97 motherboard, like the I5 4690K. Otherwise if you have no plans to overclock, you should be able to find a cheaper H97 motherboard. If you are interested in high speed RAM, then you should opt for an overclocking motherboard and processor as non-Z87/Z97 motherboards will not run RAM at speeds above 1333/1600MHz. If your current parts list is already above your budget, you should cut back and look for a cheaper motherboard. Depending on certain factors, you could look at B85 or H81 motherboards - they are often available for cheaper and are technically compatible with the i5 4460, as long as they have the proper BIOS revision. You may need to check with the retailer before purchasing, but generally speaking unless it's very old stock, B85 motherboards are sold with new enough BIOS revisions to support processors like the i5 4460, otherwise you could go with the older i5 4430 which is slightly cheaper and compatible with H81/B85 motherboards out of the box, no BIOS version checking required.
Just 400 watts would be cutting it very close to the limits of the power supply. With the GTX 970, 500 watts for the entire system is recommended at the very least. If you are not overclocking, it may be possible to go under that recommendation, but the more wattage you have to work with, the better.
According to tests by Guru3D, the GTX 970 will draw a bit less than 200 watts, and they do recommend a 500 watt power supply.
Give me a couple of minutes, I'm exploring geizhals.de, it seems to be very comprehensive. I'll have a cheaper non-overclocking PC parts list for you soon. I like geizhals.de, they have better filtering options than PCPartPicker does.
CPU:
Intel i5-4460
Motherboard:
Gigabyte GA-H81N-D2H
RAM:
Team Group 1x8GB DDR3-1600 CL9 RAM
SSD:
Crucial BX100 500GB
GPU:
EVGA GTX 970 SuperSuperClocked
Case:
Silverston​e SG08B-LI​TE Mini IT​X Desktop ​Case
PSU:
EVGA 600B 600 watt bronze power supply
Here's the list in PCPartpicker. Each item links to the specific retailer's webpage. I don't know about shipping costs or taxes, as I can't actually read German.
PCPartPicker part list /
Price breakdown by merchant
Other: Silverstone SG08B-LITE Mini ITX Desktop Case (€61.69)
Other: Intel Core i5-4460 3.2GHz Quad-Core Processor (€171.21)
Other: Gigabyte GA-H81N-D2H (€53.53)
Other: 8GB PC 1600 CL9 TEAM Memory (2x4GB) retail DDR3 (€55.51)
Other: Crucial BX100 500GB 2.5" Solid State Drive (CT500BX100SSD1) (€175.39)
Other: EVGA GeForce GTX 970 4GB SSC ACX 2.0 Video Card (€349.00)
Other: EVGA 600B 600W 80+ Bronze Certified ATX Power Supply (€57.32)
Total: €923.65
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2015-04-21 13:07 CEST+0200