Trust your own ears. That's all that matters.
You can't going to get much/any bass out of a soundbar, so you'll need a subwoofer if you care to hear lows. Cheap subwoofers can sound terrible, (and that's what's going to come with these soundbars if they come with one) so you might be better off with conventional speakers.
You aren't going to get much "surround sound" out of a soundbar - even the most costly soundbars that claim to provide a surround effect.
Again, go listen with your own ears.
I use a fairly high-end soundbar - Definitive SSA-50 - along with a good sub (Rythmik) and conventional surrounds and front-wides. It's a compromise, but the only reasonable solution in my situation.
I have my TV on a swivel between my living room and dining room. I can watch from the LR, DR, or kitchen. As a practical matter, I needed speakers on the TV. So, left, right, and center on the soundbar. This is both to be able to direct sound to the viewing area, and because of the limited space in the area between the living room and dining room.
The soundbar also does a "fake" surround with carefully-positioned/aimed speakers and some acoustic processing. (Basically matching the frequency response of the earlobe modifying sounds arriving from the rear). I find the effect "meh".
I disable the surrounds in the bar when viewing from the primary viewing location, using a remote relay.
If you do not have constraints (space, aesthetics, variable listening area), that dictate the use of a sound bar, you are almost certainly going to get better sound at a lower cost using conventional speakers.
But, again, always let your ears be your guide. You need to balance your constraints and desires against what you consider to be good sound.
$500 is going to be tough. You're not going to get a receiver and decent speakers for that.
How important is surround? If not, get a pair of decent self-powered speakers, like Behringer, and call it a day. Not sure what to do about center, then, though. And oh, ack, you have to buy at Best Buy...
Looking at that room, I don't see the problem with wiring-in surrounds. Pop the baseboard, cut a channel behind it (unless a rental...). Don't get speakers with built-in wireless. You can get wireless adapters that can be used with any powered speaker, then you have your choice of speaker. But I think it runs about $100/channel, so that blows your budget. Pop the molding.