Never had a really great experience with any computer shop.
I bought my first Amiga 500 with 1084S monitor and 2400 baud modem at the 1988 World of Commodore in Toronto from a dealer who had a booth there. Since I was either 17 or 18 years old, and had never purchased anything that expensive before (about $1000 CAD) I asked my Dad to do the transaction for me, and I would reimburse him with the cash I had saved up. One of the enticements to the sale was that we could visit the dealer's real store anytime and copy public domain software from his library.
Well I guess that he liked credit card bearing adults better than teenagers, because when I showed up at his real store and explained that we were here to copy the PD software as promised, he was a lot more gruff and limited the number of PD disks I could copy to something like six.
Then in the mid-1990s I would sometimes visit one of the only Amiga stores left in the Toronto area. It was in the west end beside one of the westernmost subway stops. One week I purchased a used Amiga multi-sync monitor from them for around $300. The next week I purchased a high-density floppy drive (Amtek?) from them that cost nearly $200. I told the saleperson that I had experienced problems getting HD drives to work with my A2000 in the past, and I asked if it would be a problem to return the drive if I could not get it to work. He told me it was no problem.
Well, the drive just wouldn't work as a HD drive in my A2000 despite trying EVERYTHING (jumpers, cable swapped wires...all the jazz). So I brought it back within 24 hours. The owner refused to give me a refund at first, and when he finally did he said he was deducting $30 from the refund as a 24 hour "rental fee". I argued that was unfair, especially since I had just purchased an expensive monitor from them. Since he had my money and there was no other way to get it back I had to accept the $30 "fee". If I had more wits about me I should have called VISA or the Better Business Bureau and complained. But I was younger at the time and didn't have experience with these sorts of things. I never went back there and eventually they went out of business.
But I haven't had great experience with PC shops either. My wife was looking for something to get me that I could "actually use" this past Christmas and I suggested I could use some RAM for my slightly older PC (needed two 1GB memory modules). I did my research and looked up the exact type of memory modules that my motherboard needed from the manufacturer's website and manual. I wrote down the specs (an exact quote from the manual) on a piece paper for my wife. Since these were going to be used parts, I directed her to the local "mom and pop" computer store which I normally liked to support instead of the "big box" stores.
She went in one day after work and explained that she would like to buy some older RAM modules and that she didn't know much about much about "computer jargon" but that (her husband) had written down what he needed. The fellow took the paper and said something like "well it looks like he doesn't know much about computer jargon either" as if what I had written down was jibberish. He then tried to tell her that it wouldn't be compatible but that she could buy such and such a new part (this was the owner of the store who had run it for over 10 years).
I was pretty frustrated with this arrogant response. I took the specs, went personally to ANOTHER computer store (I won't be going back to that first store again) and within 20 minutes had returned with exactly the RAM modules I needed and had my PC's memory upgraded. As a bonus, it was cheaper at the second store.