You don't have to guess
My Texan friend Jason once put it like this: "Sure, but people here in the States cannot buy one of your systems. I know some local shops that are good, and some that are horrible, but that is only because I was in the business. Most people simply have to guess."
No you don't have to guess! You can quite easily find out who does it right.
Method #1. The best method — and it's completely non-technical — is to simply ask friends and family who they bought from and how happy they were with the service. This method can produce mistakes, of course, but on the whole it works quite well. We, for example, get approximately 80% of our new business because of personal recomendations.
Method #2. trial and error. Most people buy quite a number of PCs over their lifetime. You take pot luck and buy from someone different each time until you are happy, then you stay with that vendor. Not very efficient, but it works eventually.
Method #3 requires some technical knowledge. You may not have it, but you are almost certain to know someone who does. Get some quotes that detail the system components. Take the quotes to your technical friend and ask him which ones are using quality components. He should look for the tell-tale signs like brand of motherboard, brand of optical drive. Does it have a U Series Seagate drive? Cross that one off the list. Is it a cheap, no-name keyboard? Cross that one off too. And so on.
Method #4. Find out how long they have been in business. Two-thirds of the longer-established places are good. Two-thirds of the newbies are bad.
Method #5. Look at how much they advertise and what they say about themselves. Shops that don't advertise much are either so successful that they don't need to — their regulars keep coming back — or so bad that they can't afford to pay for advertising and are not long for this world. It's not hard to tell the two apart.
Method #6. Look at the price. If they are really cheap, they are nasty. Good quality and good service costs money. If they are significantly above the average going rate, then they are either really good and charge accordingly, or else just very greedy. This is the hardest distinction to make of all. You are well advised to resort to method #1 at this point.
Now, by using one of methods #1, #2, #3, #4, #5, or #6 you are not 100% certain of finding a good dealer, but the odds are in your favour. Let's say about two chances out of three. If, on the other hand, you go to one of the vomit box makers, you are virtually 100% certain of getting junk. And paying too much for it.
Which is better? A sixty-six percent chance? Or a zero percent chance?