Thank you everyone for your advice and insights. It's been very helpful.
The dive shop has been in business for 45 years. I suppose that's not necessarily a guarantee of anything for the future though. It is actually free servicing, not just parts. However, good point about how often they do that servicing, etc. I will have to ask them to clarify all the conditions.
What would you recommend for this set of gear, (and what would you recommend for a computer)? I do hesitate to blame the shop, as they did offer a range of options on the mask, fins, etc. where I could've got a cheaper set. I knew next to nothing about diving when I made these purchases, however, so I picked their mid-price-range stuff as I was afraid of going the cheapest route. I should've done my research beforehand. I don't mind the $80 for the mask so much, as I had to try several to find one to fit my face and I'd rather pay a little more for a well-fitting mask. The fins and booties though I could've got for much less lightly used. And yes, I really regret the $50 I spent on the dry snorkel, when the cheap snorkel that I already owned would've worked perfectly fine. Again, knew next to nothing about diving, didn't realize that you didn't need a special snorkel for it. But I should've done my research, so I don't know that I can blame the shop (maybe I can?).
I will look into learning to service gear myself as that does appeal to me. From everything I've read, I was under the impression that servicing less than annually was considered risky/unsafe. Is that just an industry recommendation and is it common for divers to service less often or only when problems arise?