I recommend a
Blackburn Mammoth mini pump. It's not gonna let you down. Many places blow them out for 9.99. Just google it. It's a
great quality high volume pump that will inflate the tire fast every time.
Second...you need a comprehensive
good quality multi-tool. Not just a decent one. People will give you all sorts of advice here, but the type of remote riding you're planning should necessitate a tool with everything you need. I like the
Specialized EMT with the chain breaker on it. I have a Park I-Beam for when I do local and urban stuff, but most of the time, the EMT is the one I pack.
My tires fit tight. The tire levers on multi-tools can scar my rims. I like to pack two
Oakley tire levers. My crappy bike doesn't need them b/c the tires go on easy by hand.
I ALWAYS carry a
derailleur hanger to fit my Komodo in my pack. If I ever snap the sucker, I've got an extra. B2B made alot of sense the other day when he suggested carrying an el'cheapo derailleur in the pack. The last time I broke my hanger, I also broke my cage...so the spare hanger was useless. A new RD is quick and easy to pop on there. I don't know if I'll follow that advice, but it's smart.
As far as tools go...that's a decent list. Alot of people will carry cell phones, gps, pocket knives, goofy hand sanitizer (what???!!), first aid stuff, yada yada...
I usually do a
spare tube, my cell and pager b/c 80% of the time I ride "on-call" at work, water, and sometimes
food depending on how long the ride.
As far as "where to buy"?
For the small stuff...give your
local bike shop some love. If you're not gonna save $50...don't get it online. Snag a good tube and patch kit from the LBS.
Regarding a seat bag...LBS is a good place...but think about a
hydration pack to wear on your back. It helps to have the weight on your back when standing to pedal...that weight converts to torque on the pedals. A pack can hold more & you're gonna carry water anyhoo.
Camelback MULE is excellent...I roll with a
Dakine Drafter that I really like. I have a smaller Dakine Shuttle for shorter rides...but I find myself just grabbing the Drafter most of the time.
I think the most important thing with MTB'ing is that you need to get good quality stuff. Don't buy a cheap hydration pack b/c it wall fall apart on the trail, or the bladder will leak water. Cheap multi-tools will round off, break, fail, mess up your bike. Cheap pumps just don't push any air...for some reason though...the Mammoth has been soooo inexpensive at times...it's a very good pump. Cheap tire levers will break. There are tire levers out there that have a steel or aluminum support rod in them...but for the most part those aren't needed outside DH/FR applications. Pedro's levers are beefy plastic that isn't brittle.