Definitely talk to your fellow Massachusettsans (?) about patching. Recorders are so good now that what matters most is the incoming signal. Hook up to someone with super mics and you will have a great recording.
But of course you'll want your own.
Since budget is important and you are recording amplified bands, you really don't need a preamp at this stage (or possibly ever). A battery box will save you $100 or more, even over a starter preamp, and it's all you need. Preamps, well, amplify the signal from your mic. But a loud concert doesn't need to be amplified--all it needs is for power to be sent to the mic to make it perform at its best.
What you do need are mics that take plug-in power (which is low enough to be supplied by the recorder, but better supplied by a battery box). Phantom power is 48V, needs a separate box, not for a starting setup.
You also need to decide whether you want cardioid mics (which are directional) or omni mics (omnidirectional). I am in the omni camp--it sounds richer and rounder to me, because budget cardioids have less bass and because, at times, recording with cardioids and listening through headphones gives an odd "backless" sensation to the stereo, as if there's a void behind you. (Though if there's a chatty audience I'd long for cardioids to shut out the yappers behind me.)
Again, cardioids are directional. In a fixed position, on a mic stand, that's fine--the whole concert doesn't swing around as it would if you moved them. But stealth recording can also mean just clipping the mics to a shirt collar, glasses, etc., and if you do that you are going to be less happy with cardioids. Omnis are more forgiving. (Also, if it's a factor, they can handle wind noise better in outdoor situations.)
Really, go to Live Music Archive and listen to mics you are considering--you'll find plenty of material from your chosen bands.
Core Sounds were once many tapers' choice but now there are options that are cheaper with better sound. Church Audio was mentioned above, and I love the CA-14 omnis. They are not the stealthiest thing--size of the tip of your thumb--but in the dark at a show, people aren't looking at you.
Since I got those, Chris Church (who makes everything by hand) has said his CA-11 are even better omnis, and they are also smaller (CA-14 is built into a foam windscreen). You should think about those and get the $29 Ugly battery module with them, which is basically a gizmo that snaps onto a 9V battery. Church Audio is in Canada, so shipping adds time and price, and is slow to deliver--you'd join a long queue and might not get the mics before October--but they also show up in the Yard Sale here.
I haven't used the Tascam, but I can tell you that the Sony PCM-M10 is one solid and easy to use recorder. Also, with its simple rectangular shape--its mics are recessed--I've had many security people think it's a point-and-shoot camera. I can in good conscience promise not to shoot one photo with it.
Mics (with clips for shirt/glasses mounting), battery box, PCM-M10. Very happy with countless shows recorded that way.