For an update on this, a few people have sent me some pens to study/use, and for that generosity I am very thankful. In addition to this I've bought some pens (both new and used), some different inks and at this point can tell you this:
1. if you want a very cheap but very nice fountain pen, there are a few I'd suggest: Preppy by Platinum. Nice ink cartridge, easily refillable with a syringe and should last for decades. Pen body is not bad, but is not designed for heavy duty, so don't abuse it. Pilot Varsity (or V-Pen)...these are disposable, but you can refill them with a bit of work. Pilot Petit1 (mini-pen). These can be bought for $4 or less each. They're all very pleasant to use. In fact, you can write with the Preppy and Varsity for hours on end with no fatigue. The Petit1 is a finer point.
2. if you want a nicer but still not expensive pen, you might want to look at the Noodler's Flex series. $14 to $20 will get you one, and it will be very nice to use. Added note: this pen will go dry sooner than the Preppy or the Varsity. It operates wetter and the top does not seem to seal nearly as well as the cheaper pens. It has a fairly aggressive feed.
3. I've learned the feeds are very different between various makers. There's much more variation here than I expected. Some have dual top slots, some have slots on the top and bottom, some use a vented central feed line and some use pretty imaginative feed schemes. Some pens I've received no longer worked due to failure of the feeds...clogged, inserted wrong, slipped out, etc. I'd say this is the weakest link in old pens.
4. Bamboo works ok as a nib, and it can be quite pleasant to use on a variety of papers. It is however fragile, shaping it is a slow process and I've not yet found an ideal feed scheme for it. It has the unique quality of absorption which means changing colors is not easy. Still of all the alternative materials I've tried so far, this is the most encouraging. It is in my opinion going to be best suited to use at a desk rather than carried around. But there are ways it may be improved. It is certainly eco-friendly.
Jon