c02 generator help please

looking at the following system for producing co2 http://www.plantlightinghydroponics.com/cap-gen1elp-liquid-propane-2burner-electronic-co2-generator-p-1889.html
i can handle the extra heat and humidity (have dehumidifier and air conditioner) and ive been reading that propane is 6x more efficient than the tanks
the guy ive been reading about has a room half the size as mine (10 x 12) and he uses 2 tanks a month.......thats too much work for me
the propane is 20# for about15$ and i have a refill place close and extra tanks are 35$ compared to 150$ for co2
that being said......
until i get some extra cash can i use this system without the controller ?
ill have the extra money after another grow
i can estimate the amount ill use and if im a little off with propane its kinda cheap
id have to change my tank 3 to 4 times a month with the liquid co2 while with propane its about once every 6 weeks and its cheaper to refill
can i just use a basic timer ........does it have a prewired plug?

What about a propane fired instant hot water tank? I know there are some threads here on how to do it.

You can usually find a set-point controller for about $350 on ebay.

it will cost me a minimum of 700$ each room with 800$ being more realistic with tax/shipping

is there a cheap wayof filtering in carbon??

I have seen a water cooled Co2 burner for about $350, and propane water heaters for $250. There is a water run off, so you would have to cool that run off some way to avoid waste.