Well, since your not sure if you'll continue to play then I agree that you don't need to spend more than $300.
I would advise that you try out as many guitars as you can at a few local stores. Just to get an idea of how nice a guitar can sound and feel, try out a higher end, expensive guitar (avoid salepeople if you can, especially most Guitar Center sales people). Then jump down to one about half the price and continue on down until you find one that feels and sounds right for the price.
The tone will be something that you'll have to decide on but as for the playability, I try and play each string on every fret and listen for any strings that buzz annoyingly. You shouldn't have to press the strings down so hard that it hurts your fingers or hands. Try learning a couple 'bar chords' and try to play those at different positions along the neck as well.
Since your budget is limited you probably will have to deal with a certain amount of string buzz. I think that 'test driving' is the only way to go .
You can try getting an inexpensive guitar that sounds good with just a small amount of buzz and then have a local luthier work his magic with a 'fret dressing' and/or new nut installation. A good luthier can make a low end guitar play pretty nicely.
Most music stores either employ or contract luthiers. When you are ready to purchase a guitar you can ask the store to have it 'set-up' before you buy it.
Long winded but I hope this helps. Good luck!
P.S. Keep us posted on what you get.