Another dumb question from a hanging newbie. I'm looking for a good rainfly for my hammock that will keep me dry during some heavy rain and provide good wind protection. I want it to cover a good amount of space but I also want it to be light and able to pack small. I also don't have that much money to spend. I was wondering if cheap ones are any good.

For the most part, it's a cost/weight/size tradeoff. A standard polyethylene tarp will work, but be heavy and bulky to carry ($10, 30oz, 8'x10' or $20, 90z, 15'x20' from Target).

Polyurethane-coated nylon or polyester tarps like the Kelty Noah's Tarp 12 ($70, 33oz, 12'x12') or ENO ProFly ($80, 22oz, 6'x10'), or ENO ProFly XL ($100, 28oz, 9'x13') are the next step.

After that you have silicone-impregnated nylon tarps, like the ENO ProFly Sil ($120, 13oz, 6'x10'), Warbonnet Edge ($85, 11oz, 8'x11'), and Cooke Custom Sewing Tundra Tarps (eg. $89, 24oz, 8'x10', 1.9oz fabric; $115, 37oz, 10'x12', 1.9oz fabric; $126, 14oz, 8'x10', 1.1oz fabric; or $189, 22oz, 10'x12', 1.1oz fabric).

Finally, there's cuben fiber tarps, like the HammockGear Hex Tarp ($235, 5oz, 8'x11'). Does not apply for people concerned about budget. :P

Besides those concerns, you'll want to think about the shape of tarp you want. Some are a catenary cut, intended to pitch as a diamond but also functional as an A-frame (Noah's), others are rectangular and work well in A-frame and lean-to setups (Target, CCS), and some are a hexagonal design meant specifically for hammocks (ENO, Warbonnet, HammockGear). Finally, there are also tarps with "doors" that can be closed to cover the ends to keep out the wind, which is useful in strong rainstorms and anytime in the winter. These include silnylon options like the Warbonnet SuperFly ($130, 19oz, 10'x11'), Warbonnet Edge plus detachable door kit ($160, 19oz, 8'x11'), or Warbonnet Mamajamba plus detachable door kit ($185, 22oz, 10'x11'), and cuben fiber ones like the HammockGear Winter Palace ($395, 9oz, 10'x11').

In terms of the size, my smallest tarp is an 8'x10' CCS, and that just barely works. It's a great tarp, but doesn't give much coverage overlap on the ends of my hammock, and that's on a 9' hammock - the more common 10' and 11' sizes would require a larger model like their 10'x12' or 10x14'. The 12' Noah's has plenty of coverage, and things like the SuperFly and Winter Palace are, well, palatial.

So, it all depends on your budget and what you're willing to carry. I'd be inclined to steer you towards the SilNylon options if you can, in sizes 8'x11 or larger and weighing 24oz (1.5lbs) or less. That puts you in a budgetary range of $85 to $190, or if you'll be in conditions where having doors would be useful, $130 to $185, but if you can't swing that right now you can always get something cheaper to start with and acquire a second tarp later as finances allow.

no such thing as a dumb question(except the one you should have asked when you are cold, wet and miserable standing 20 miles from anywhere).
It is the old saw...light, durable, cheap...pick two.
tony is spot on.
You say $$ is tight? The Kelty is very popular for its durability and larger size. Play with it a bit and learn various rigging configurations.
If you fall into some extra samolians think about the CCS, Warbonnet, etc.
When canoe camping the weight penalty is minimized because portages are really not very long hikes.

Some good advice above. They are the voice of experience.

I've got both a Guide Gear 12' and the Kelty Noah's 12'. Both served me well for years through some very severe coastal storms. But, they are heavy.

The Guide Gear cost me only $20 (on sale) back when the quality was top notch. People are complaining about the quality in recent years.

In January, I acquired the Hammock Gear 11' standard cuben fiber tarp. Have only used it about seven nights so far -- with no major storms -- but it seems to be a beauty. It weighs almost nothing.

Like others have said, you cannot go too far wrong with the Kelty for starters.