I am currently searching for a good antenna that would best fit my needs and as inexpensive antenna that does what I need it to do.
I am not sure if I'll need a Yagi or Discone, but I live in an area that is a bit lower ground and pick up my closest cities pretty well but I am looking to expand my receiving range out farther. If I am right, since I am trying to expand my range out to areas in multiple directions, I'd need a discone, correct?
Depending on what I might need, does anyone know of some good inexpensive options? Either an indoor or a rooftop antenna.
A Yagi antenna is going to be directional. They are primarily designed to work well in one direction. That "direction" can be a pretty wide beam width if you go with a lower gain antenna, or quite narrow with a higher gain antenna. They are still limited to maybe a few tens of degrees at most.
If everything you want to listen to is in one direction AND on one band, then a Yagi might be a good choice. There are some Yagi antennas designed for amateur radio use that have elements for 2 meter VHF as well as 70 centimeter UHF.
If you want to listen to traffic from more than one direction or across a number of bands, then a omni-directional antenna will probably be a better choice.
If an omnidirectional antenna is what you are looking for, then you need to decide what frequencies you want to listen to. If it's one or two bands, then a simple vertical designed for those bands will work best. If your answer is "everything", then that pretty much leaves you with a discone.
Trouble is, discone antennas are mediocre performers. They exhibit 0dB gain, which means they don't do anything to increase coverage over a simple ground plane antenna on a specific frequency. That's the trade off you get if you want to listen to "everything".
Important part to consider is that the antenna is only part of your system. You need to pay attention to how you mount this antenna. Since you mentioned you were in a lower area, you will need to get the antenna up high. The antenna needs to be able to see (for the most part) what you are trying to listen to. How high that needs to be depends on just how low you are.
Your coaxial cable is very important, too. If you use cheap coax, you'll lose most of your signal in the coaxial cable due to loss.
So, before you go looking for a cheap antenna, make sure you consider the entire system: Coax, support, antenna, plus all the little things, like waterproofing your outdoor connections, securing and routing cable, connectors, lightning protection, etc...