The evaporation of hexane is endothermic. n-Hexane has a low enthalpy of vaporization at $31.56\ \mathrm{kJ\ mol^{-1}}$ at $25^\circ \mathrm{C}^{[1]}$, compared to water, which is $43.99\ \mathrm{kJ\ mol^{-1}}$ at $25^\circ \mathrm{C}^{[2]}$. This means that hexane quickly and easily absorbs heat from its surroundings, and can get well bellow $0^\circ \mathrm{C}$. Indeed, I recall performing an experiment in high school whereby a paper towels dipped in different solvents were wrapped around the end of a thermometers, and the lowest temperatures were recorded. By far hexane was the lowest at something below $-10^\circ \mathrm{C}$.
n-Hexane is definitely not a fertilizer, and doesn't do any serious damage to the environment like chlorofluorocarbons do. Your main concern would be storing it in a cool well ventilated space and keeping it away from open flames, as it is very volatile and flammable. Additionally I would recommend you work with nitrile gloves, as they are insoluble in hexane. Hexane is a very non-polar molecule and can dissolve your epithelial cell membranes. It's not immediately dangerous, however, so just take caution not to get too much on your skin.
If you find hexane too hard to obtain, acetone would have similar qualities, and is easily obtained at the grocery store as nail polish remover.
[1] Majer, V.; Svoboda, V., Enthalpies of Vaporization of Organic Compounds: A Critical Review and Data Compilation, Blackwell Scientific Publications, Oxford, 1985, 300.
[2] Marsh, K. N., Ed., Recommended Reference Materials for the Realization of Physicochemical Properties, Blackwell, Oxford, 1987.