I finally decided to try out Amazon Prime, their deal where you pay $79 to get unlimited two-day shipping on everything you buy for a year with no minimum purchase requirement. I don't think that it will pay for itself in dollars, but I do hope that it will pay for itself in convenience. Had I started on Prime a month ago, I think I'd have already saved $15 or $20 of the membership cost, too.
If it weren't for blasted sales tax, it'd be a no-brainer, but since things I buy from Amazon cost 10% more than things I buy elsewhere, Amazon is not often quite the cheapest, though they seem to be pretty good for most things nowadays. Probably close enough that it's not worth shopping around now that I've pre-paid for a year's worth of shipping charges, and certainly cheaper if you factor in the cost of two-day shipping at other stores that I haven't pre-paid shipping at. Shopping around to save a dollar kind of defeats the purpose of paying Amazon $79 a year so that you don't ever shop around.