Building one is always better as you can customize it according to your needs. More importantly, you avoid having to pay a premium over branded ones.

Would help to know what resolution you are planning to run eg 1080p, 1440p, 4k and the kind of games you are into. Also, your RM4500 budget is inclusive of monitor and other peripherals like keyboard, mouse, etc or just for the rig?

with that budget , u can smile already

but still. wait for ryzen review out and u can finalize ur built

btw u can start finding other piece

1. NVMe Pcie ssd  : either samsung 950 or intel 750 is good
2. HDD : 1-3 tb is ok.
3. RAM : minimum 8gb.. preferably 16gb. kingston fury X is good budget already. u dont need high performance ram aka pricey ram tbh
4. GFX : this is the large chunk of ur budget.. check out last year 1070 or 1080 ( meanwhile the next gen gfx is around the corner already from AMD and Nvidia )
5. CPU & motherboard.. expect 2k budget here if u want ryzen 7 or i7

Sometimes you just can't wait no more. That happened to me once.
But how soon do you "need" this pc rig, eh TS?

with that budget , u can smile already

but still. wait for ryzen review out and u can finalize ur built

btw u can start finding other piece

1. NVMe Pcie ssd  : either samsung 950 or intel 750 is good
2. HDD : 1-3 tb is ok.
3. RAM : minimum 8gb.. preferably 16gb. kingston fury X is good budget already. u dont need high performance ram aka pricey ram tbh
4. GFX : this is the large chunk of ur budget.. check out last year 1070 or 1080 ( meanwhile the next gen gfx is around the corner already from AMD and Nvidia )
5. CPU & motherboard.. expect 2k budget here if u want ryzen 7 or i7

With your budget, running games adequately in 4k will be challenging. Below is more suited for 1080p and possibly 1440p with lower in-game settings:

1. CPU - i5-7500 (RM899) - can save some if go for i5-7400 (RM835)
2. MOBO - Gigabyte GA-Gaming B8 (RM589)
3. RAM - GSkill 2x8Gb DDR4-2800 (RM649)
4. Gigabyte GTX1060 Windforce OC 6GB (RM1385)
5. PSU FSP HEXA+550W (RM229) - I would suggest a better PSU eg SuperFlower Leadex Silver 650W (RM399)
6. Case - Fractal Design Defince C window (RM399)
7. SSD - Samsung 850 EVO 120Gb (RM299)
8. HDD - 1TB 7200rpm (RM219)

Total - RM4668 before "rebates" from Idealtech.

You can check it out here.

thats what i mean.

With higher performance requirement, you will need to up your budget. As suggested by the others, you could squeeze on things like casing and RAM to free up some budget.

If you are not in a hurry, hold off for a bit. News of Intel reducing their prices across all their SKU is starting to hit the market. Good times ahead for consumers