If you are using the TV for the monitor, check how it's speakers sound, some have decent speakers. 95% of the sound quality is from the speakers, at least at the lower level of equipment. If you are using HDMI to connect to the TV, you can setup the speakers easily using the TV audio outputs.
I have had good results to get better sound with a soundbar, I have a Vizio one and it sounds good, for about $100 and can find them for less, especially used. Easy to setup although you don't get the full surround sound thing. Make sure it has other inputs so you can connect other computers to the speakers, mine has a mini jack for sound as well so I can hook up a laptop to the speaker as well as the TV output.
If you want to use surround sound and not just have it simulated, you can get a 5.1 all in one setup for a bit over $100 for to start with, and $200 for a decent setup to use with the TV.