1. All shops will tell you to liaise with distro after 7 days from purchase for any issues. I think the only for a shop to help u RMA at their cost is if you know the boss very very very well.
2. Possible to get discount if you open your mouth and choose your words and tone wisely. If not, consider getting from online and self assemble to maximize ur savings.
What Bro shadow84 say is right.
Discount is also best done when you really really done good amount of homework on the prices. You can check online such as Newegg, Qoo10 or Lazada. Some local shops tend to have online shops on Qoo10 and Lazada.
It is best to have a set budget with some room for adjustments. Then roughly have some requirements for what you want to have in your build. Then say for example, you want a 500GB Samsung ssd, you can actually look for the prices online. If possible apply discount codes, credit card rebates, shopback, anything to bring the value at low as possible.
You have remember to look out for warranty. Some brands purchased from online do not have or have other means to get your parts RMA. If parts really have no warranty, it voiced down to the value. Is it worth the value?
Then once you get a value, if you comfortable with it commit, otherwise do more homework and check on price list from Simlim. It will also benefit much more if u can ask the physical shop for the price. The price can sometimes differ from the price list. The price lists are changing every week. And some shops sell with different margins even within the shop itself, sometimes the sale person can quote differently.
Then everything settled, buy liao. However, please remember it does take effort and time to get the best value of a part if you are budget mindful. Online discounts will have timeline. They will expire and change. You will need to keep track on it.
Try to keep yourself informed of the current prices so even when you seek discounts you roughly can gauge ($10 to $50) and not ask ridiculously. (You can test the water, at most the shop doesn't sell you.)
For warranty, Bro shadow84 say liao le. You can do a check on most distributors, particularly on the location and operating time. Some places can be really be out of the way. Then those operating Monday to Friday, you need to spare your time from work or other commitments. Some like CDL Trading do open on Saturday so I quite like it. Distributors may carry same or different brands so look out for the stickers on the retail boxes.
Lastly, remember to keep all receipts. Easy to RMA. However if lost, check with distributors first. Most of them can rely on the RMA sticker on the parts itself.