What is your weight?
You could start with a Grand Trunk Ultralight for $20 (http://www.campmor.com/outdoor/gear/Product___40675) and add whoopie slings, tree straps and a couple carabiners (see http://www.whoopieslings.com) Those suspension items can be used on other hammocks if you decide to upgrade.
Regardless of the hammock you buy, you will need bottom insulation of some sort and 20" wide pads don't cut it. You can pull it off with a wider CCF pad (see Gossamer Gear, etc), but the real comfort of a hammock is best with an underquilt, which will add a lot to the cost. Tarps are typically larger than ground tarps and made of the same gamut of materials. Your hiking sleeping bag or quilt will do.
And then there is hammockforums.net, a collection of freaks on hammocks on the same order that ultralight is here :)