I want a cheap altimeter/barometer dammit!

[johnniet]

There's got to be a decent tool for measuring air pressure for less than $30. I just want to be able to check my altitude while biking--to within 50' or so. Is that so unreasonable?

 

[diletante]

There are a few items on eBay that might meet your criteria LINK

 

[Cougar Allen]

Take a look at www.casio.com -- and keep in mind the prices listed there are "list prices" -- ie, look for something with a list price <$50. I'm not sure if they have a watch with an altimeter that cheap or not. Even if it's a little more, though, it'll have other functions that are likely to come in handy. No doubt you already have something with most of those functions, but it can be handy to have a second stopwatch, countdown timer, etc.