For the most part, I agree with your comments, Jay, but....
jdef said:
When you make up a developer from bulk chemicals you don't have to pay for advertising, packaging, shipping, R&D, manufacturing, etc., etc.
Actually, you
do pay for many of these things when mixing from scratch. Certainly you pay for packaging, shipping (to your door or to a local store), and manufacturing of the raw chemicals. I doubt if R&D is a significant cost for these chemicals, but many of them are advertised -- if nothing else on their retailers' Web sites. Still, the main point that it's less expensive is very true. I put together a spreadsheet a while ago to help me assess the cost of various developers, and the mix-it-yourself type is almost always cheaper than the commercial type. Oddly, though, the reverse is true of fixers, at least those based on sodium thiosulfate -- the cost of that chemical (or more likely, of shipping it) is just so high that it wipes out the cost benefits of mixing it yourself. Maybe with an adequately cheap local supply source this would change, but so far I've not found one near me. (I confess I've not really looked all that hard, though.)
I can't count the number of threads I've read, dealing with the issue of availabilty of a favorite developer. These kinds of problems will persist, and worsen as the market evolves. By making your own developers, you free yourself from these concernes
One caveat on this one: A few critical developer components, such as metol and phenidone, seem to be readily available only from photographic specialist outlets, such as Photographer's Formulary and Art Craft. I don't know if these items are used for anything
but photography. If not, the supply of these items could eventually dry up and/or the price could go up substantially in the years to come. Of course, I expect that
somebody will continue selling such items to the general public for as long as commercial developers are available, so I doubt the home brewers are really in any worse a position than are those who use the commercial products. There are also developers like Caffeinol, which use no such specialist chemicals. In a worst-case scenario, a home brewer who notices the supply dwindling could purchase a lifetime supply of favorite at-risk components. (For phenidone, that'd be a few grams!)
)
I haven't found those at general-purpose chemistry suppliers -- at least, not those that sell in quantities of a few dozen or hundred grams to end users. I know hydroquinone's used in some skin-care products and glues, but I don't know what the others are used in, aside from photochemistry. (A search at 
