Hi xandallf ,
If you can wait until 21st Aug (less than 1 week away), Intel will be launching Coffee Lake CPUs, so it will be better to wait and compare between Intel & AMD. You can always buy the rest of your components first (besides the casing) while waiting for the CPU.
But if you need to buy your PC now, I have the following suggestions (shop names in brackets). Ryzen 5 has 6-cores 12 threads versus i5-7500 which has 4-cores 4 threads. Ryzen 5 can also be overclocked using B350 motherboards.
Prices shown before any discounts:
CPU & MB Bundle: Ryzen 5 1600 & Asrock AB350M Pro 4 @ $452 (Dynacore)
RAM: G.Skill 2400Mhz 8GB @ $90 (PC Themes)
GPU:
Palit GTX 1070 Dual Fan 8GB GDDR5 @ $632 (Qoo10)
SSD:
Western Digital Blue 250GB M.2 @ $136 (Lazada)
Hard Disk: Toshiba 1TB 7200RPM @ $63 (PC Themes)
Casing:
Tecware F3 @ $45 (Lazada)
Power Supply:
Superflower Leadex Silver 90+ Full Modular 650W @ $128 (Lazada)
OS: Windows 10 @ ~$12 (Carousell)
Total Cost = $1558
Qoo10 has $100 discount coupon (min. $600 purchase) that you can use for your GPU purchase. It appears once to twice per month. For more discounts, you can also buy $100 Qoo10 gift cards (each at 3% off) and use Qpoints.
For further discounts on Lazada, you can use their various credit card promo codes, LiveUp (5% rebate) and Shopback.
Details on LiveUp and Shopback:
https://www.liveup.sg/
https://www.shopback.sg/lazada