Brocephus

Oh yeah, even down here in South Podunk, we've heard of Camelbacks ! In fact, you just reminded me that I already have one ! Years ago, I spotted a brand new one, will all retail labels still on it, at one of my local thrift stores, so I scarfed it up. I may consider dusting it off and putting it to good use, once the worst of summer arrives.
And many thanks to everyone for the wide range of suggestions. To respond to some of them.....
-Thanks, but some if the suggestions are well beyond the "inexpensive" requirement I mentioned in the OP.
-Thanks, but some clamp suggestions won't work with the larger 31.8mm bar I mentioned in the OP.
-My jersey pockets are already loaded with stuff like keys, cell phone, spare tube, CO2 inflator,etc. so a water bottle would be pushing it.
-The larger cage that will hold big Nalgene bottles was a good idea (I have a bunch of Nalgenes, they show up often for .25-50 cents at the aforementioned thrift stores), but I'm using some pretty jumbo Euro bottles already, and don;t think the Nalgenes hold very much more, and probably not enough to justify the cost of expensive new cages).
-Right now, I'm leaning towards one of the inexpensive handlebar clamps on Ebay, and a member here has PM'd me links to a couple good options (and personally vouching for the quality of one of them). These seem to be the most economical and unobtrusive options so far.
Anyway, thanks again to all for taking the time to weigh in, lots of good food for thought here........