it's true that at this time buying a pre-built pc is better than building due to higher prices. The pc you are willing to buy has a 1070Ti+Core i7-7700k-16Gigs of ddr4 ram along with a 240GB SSD.
The pc is itself very powerful but the price is the biggest factor of building or buying a pc. If you build a same PC with the same components it will run you about $1700. Each and every 1070Ti out there has a price tag of more than $800. add about $350 for a Intel Core i7-7700k, and one 16GB ram module at something around $160. but you gotta add more things like and SSD, Case and Power Supply and a motherboard. It's way too expensive to put a PC with these specifications for a lower price. So it's worth it to buy this per-built PC at this time.
The only downside of buying this PC is that you won't be able to upgrade it in future, because This PC has a propriety PSU and a standard pc case by zotac. So There are no chances to upgrade it. However, in future if you think you want some more horsepower out of your PC, then you can sell this PC for around the same price you bought it in and the re-sell value of those zotac gaming PC's are good.
So you have 2 choices, First one is to buy this PC and save money while being happy or spent even more money and build yourself a custom built one and get rid of inconvenience of selling a pre-built pc in a future.
My answer will be to buy this PC, It's itself a very poewrful pc and it will keep you happy for next years. Still you ccan upgrade Ram, You can upgrade the Graphics card and Processor.
btw all these sudden price rises in the pc market are because of cryptomining, that's why PC gaming gaming community is in trouble
Thanks for reading my answer, hope it helps (sorry for my bad English)