The Bike. The bike's a Fuji Touring something or other. I went into a bike store and said I wanted to bike across the country and what did I need but that didn't cost an arm and a leg. They ordered this $800 bike and then fit me for it. So far I like it. The shifters are toast but it has gone through about a dozen wipeouts so far so it's taken a lot of beatings. Before leaving I changed the tires to a pair of puncture-resistant Conti 2000 series. The stock pedals were replaced with a clipless type and I got a pair of shoes to fit. Soon into the ride I added a kickstand and that was a great idea on my part.
The Trailer. Initially we had planned on bringing our sons so my wife and I were each going to get one of these. Plans for wife and kids coming along fell through so this was left as my default carryall. It's called a Wike and they weigh about 25 lbs. empty. Its main benefit so far has been that everyone thinks a kid's inside so motorists are probably likelier to take it easier on me. I hope!
Camping. El cheapo, five pound, $129 polyester 2-person tent. A Kelty LightYear 3D 25 deg. sleeping bag. A ThermaRest Z-lite sleeping pad. A travel pillow. A chamois towel. A water purifier (overkill). No cooking stuff.
Clothes A bike jersey (bought en route), two bike shorts (one of them also bought en route), Shimano bike shoes, Walmart biking helmet, one pair DeFeet socks, two pair of sunglasses, bike gloves. Also brought with me a pair of sneakers, a couple of shorts, t-shirts, socks and I don't even know off the top of my head what else. I have more than I need. That's okay, I can bunch it up and use it all as a pillow because the pillow proper is lame.
Gadgets. For the bike itself I got a Garmin Edge 205 GPS trip computer. It is a replacement for a lower-tech cyclometer and tells me (when it's working) how far I've gone, speed and a variety of other data that it then feeds into my laptop and draws me cute graphics of my voyage and performance (when the software is working). Both the unit and the software are a little buggy but I'm better off with it.
I'm also bringing along my laptop with a secondary and much more useful Belkin GPS. This lets me see on a map where I am and can trace routes for me to take but I'd rather rely on my own research and plain old gut feelings. My laptop also serves as my journal writing tool, internet connection (has WiFi built in) and entertainment (movies, mp3's, etc.)
Then there's my camera, a digital behemoth Nikon D200 with a Sigma 30mm lens. Sure, it's heavy but I'm an amateur photographer so it was not up for negotiation. I did leave my other two lenses behind due to weight and bulk.
Misc. A little bike toolkit that's like a swiss army knife. A chain fixing tool thing. Air pump. Oversized first aid kit. A travel bag with bathroom toiletries. My cell phone (rarely in range to be useful). Garbage that I haven't gotten around to clearing out.
Approximate cost for all this stuff, jeez, let's see:
Bike - $800
Bike mods $300
Garmin GPS unit $250
Biking apparel $100
Sleeping bag $100
Sleeping pad $40
(not counting camera and laptop which are unnecesary for travel)
Other than the gear the big costs are the everyday stuff; primarily the food and lodging which would vary for every individual. For me, I'm averaging about $50 a night for lodging (even when counting the odd free camping night) and about $25 a day for food.