First of all, thank you for all of the comments. I love how everyone has such a specific (and strategic) method for shopping for our beasts. I don't think I know a single horse person who doesn't have their own Order of Operations (remember PEMDAS??) for hunting down acquisitions.
Mine is less sophisticated than it used to be, mostly because I've figured out that eBay stresses me out to no end. Buying is fine. But I hate the worry of not being able to return something if it doesn't work, or god forbid the ridiculous stress involved with selling something. (I know that most humans manage to overcome this, but I... turn into some sort of eBay monster). So I've slowly ended up in the no-man's-land with eBay. Small purchases don't seem worth the hassle, and big purchases aren't worth the risk. I know most people have the coveted Schumacher bridle they scored for $100 or the perfect saddle or something similar, but I've just never had that eBay gold mine.
As for Stateline and Valley Vet and whatnot. I definitely still use them. But, I will say that I might be the only one out there who goes to Dover if my local tack store doesn't have what I need.
Is my local tack store spendy? YUP. (Really spendy). And is Dover the cheapest? rarely. (really rarely).
I can think of two primary influences for my current shopping habits:
1) Customer Service.
It sounds like some of you have had equally rad experiences with Stateline, or someone else - but I have to give Dover credit on this. Over the years I've had several instances where a $100 splint boot has crapped out, or a blanket started rubbing not after the first try-on (on a clean horse) but after the 3rd wear when said blanket ended up covered in mud. Every single time Dover has been FANTASTIC about replacing broken items, exchanging muddy blankets or working with me to find a solution, even if that just meant a refund. This breeds a certain comfort for me - in that I know if something goes wrong my $40 dollar investment (maybe it was $35 elsewhere..) won't go down the drain entirely.
2) I'm in distribution.
Our company STRUGGLES to stay branded as the high customer service, not cheapest place to buy your fire hydrants and lawn sprinklers. In today's economy I promise you that this is a tough niche to fill. Most people aren't willing to consistently pay 3% more in margin for slightly more consistent customer service (I think I can admit that when things go smoothly, you don't notice if the service is exceptional - only when the proverbial crap hits the proverbial fan).
My unwavering belief that this is the right decision for our business means I have a soft spot for any other business that I perceive as having similar traits. Dover could be huge jerks, but they've saved my ass (and pocket book) enough times for me to not cringe (horribly) at the shipping prices. (oh, and I also empathize with the real cost of freight... and how currently our consumer culture is horrified if we pay more than $4.95 to magically transport 30lbs of stuff 3,000 miles, but that's my own soapbox so I'll avoid it here).
Anyway. This isn't meant to be an all out defense of Dover and their price gouging, but it is why I tend to give them the benefit of the doubt, and why I was EXTRA PISSED to feel like they were trying to dupe me - a loyal customer with their sale shenanigans. On a positive note, when I emailed them to "double check" my shipping quote and also ask them to make sure I was getting their best prices, I got a prompt email lowering my shipping price (she shoved everything into a smaller box) and let me know that one of my items was slated to go on clearance in 2 days if I was willing to wait for her to dispatch it then. That is the sort of response and attention that repaired my lost confidence pretty quickly.
All I know is that regardless of where my package comes from.. as soon as that tracking number lands in my inbox I compulsive click "track my shipment" as though that will speed its delivery to my doorstep. I'm pretty sure it helps.
I did want to make it clear that I do LOVE SmartPak. And I've had similar customer service experience with them. I suppose my current order of first Dover, then SmartPak is due mostly to the fact that I don't have a current auto-ship SP for either mare at the moment... When I do, I have to admit that SP is my first choice. I hope that makes me sound less crazy. :)