selling downloadable products

i made a pdf version of my online website. now i like to sell it. that is all i want. click a button, and sell it thru paypal. i saw a lot of plugins when i typed sell pdf online etc… which one should i use? it confused me. again all i want is just selling one pdf file with paypal. thats it.
i didnt install and activate any of those plugins to try even the ones that claim pdf selling etc.. because i was afraid that it might do something to my site, they all seem to have many features liek online shop etc confusing stuff i dont need all that