IMO, the two most neccesary items are the most expensive. Rain cover and insulation. A welcome expense to some, but I am a budget wise kind of guy. I make more than some but not as much as most. What I did was sacrificed weight for those 2 items until I feel like it is more neccesary to have cuben fiber and down. I have a poly tarp from my base exchange (like the ones at walmart but in camo) and a campmor tarp that is poly coated for winter time use(if i ever get to see winter again). I have a military poncho liner underquilt for my back side insulation that i bought at a surplus store for around $40. I have spent a total with 2 tarps and UQ about $100 for the 3 items. Hammocking comfortably on a budget is very possible, and to save when you finally yearn for those top end items is to make them yourself, also giving yourself a sense of accomplishment with your hobby as well.
"We do not go to the green woods and crystal waters to rough it, we go to smooth it."- G. W. Sears
My forum name is Fish<><; I'm in the navy; and I hate sleeping on the ground. If I didn't need ground to walk on or measure resistance to, I think I could happily give it up.