Anon-Admin's Journal: How would you do data acquisition on the cheap?

I have been working on a science project studying the effects of micronutrient deficiencies in plants. I will be building a new environment chamber soon and was looking at automating the data acquisition portion. I am a little tired of manually taking the data and know that a computer could do a better job than me. I looked into data acquisition systems and was shocked at the price. Cheap ones are $500 - $1000 for the main unit with probes costing $50 - $300. I know that a printer port is a digital I/O and can be used to do data acquisition. After spending some time looking it up, I am not finding anything on it. So how do you do data acquisition on the cheap?

I am not a programmer (other than perl) so I would need a program or a perl module to pull the data. I can build circuits provided I have a diagram of the design. I have a system and can install any OS to get the job done.

What I need to monitor is Chamber Temperature, Chamber Humidity, Chamber Light State, Room Temperature, Room Humidity, and Room Light state.
Temp = +/- .5c

I would like to monitor Chamber CO2 level, Room CO2 level, Chamber O2 level, Room O2 level, Nutrient Levels, Nutrient Ph Level, Nutrient Temperature level, Nutrient PPM (EC) level, and Moisture in soil (Does it need to be watered?)

There will be 6 plants and 6 1gal nutrient reservoirs.

With this in mind, I have a limit of $500 for the data acquisition portion of the project. So what is the best way to get the most bang for the buck?

$500 budget is a real challenge

[bughunter]

What I need to monitor is Chamber Temperature, Chamber Humidity, Chamber Light State, Room Temperature, Room Humidity, and Room Light state. Temp = +/- .5c I would like to monitor Chamber CO2 level, Room CO2 level, Chamber O2 level, Room O2 level, Nutrient Levels, Nutrient Ph Level, Nutrient Temperature level, Nutrient PPM (EC) level, and Moisture in soil (Does it need to be watered?)

There's not enough space to give you all the details necessary, but I'll outline how I'd do the project on that kind of b

If you can find used hardware...

[bughunter]

eBay and Craigslist may be another option.

See if you can find one of these DataTaker products [datataker.com] available on auction or resale.

I recommend the following models: DT50, DT800, DT1000-4000.

You'll then need to find the sensors elsewhere, but this DAS option could potentially be very inexpensive.