How do you enhance a bad listening room's accoustics without breaking the bank? thoughts?

If it is sound isolation you are after, you want to have a high STC rating (sound transmission class) for wall and floor construction.   
Currently the IBC required code minimum STC for a condo is 50.
An STC of 75 is preferable .
The primary ways of achieving a higher STC rating are mass, isolation &  attenuation.
I also live in a condo and am considering working on two walls, the wall I share with my nieghbor and the entrance wall to the corridor. Maybe with the construction of a sound isolating partition. But this takes space......

The best room treatment for me was done by accident!

My parents had a very dense hand-woven wool rug that they didn’t use anymore. Cost them around $5-6k and is beautiful so I didn’t want to get rid of it. It was nearly the size of my listening room so I put down a large felt pad on the wood floor and then placed the rug over that. It replaced a basic polyester rug that covered maybe half the floor. Immediately the sound softened and its was just the listener and the speakers.

Otherwise chairs and a couch in the room, but this rug seems to have stopped reflections very effectively.

Want a good room?  Most Tx  look gross and do little.  They are expensive. Also, tx stuck on the wall don't do much.  They have to be suspended from the wall.  Oh, no body told you that, huh. 

First, use your brain.  How many reflections do youi want left.  Do you want to listen to your system or your room.  That's what I thought.  Take your room out of the picture.  Get Eco-core 2x4 panels (the best) and make 4x8 from them. Mount them on 4x8 x1" foam insulation panels from Home Depot.  Cover with your preference. Suspend them from the ceiling 4-6" from every wall.  If you don't have line array speakers, do the ceiling also.  Carpet the floor.  Even dirt sounds better than wood or tile.  Get some sono-tubes for tube traps.  Stick them in the corners and tune for the frequency that is bad for your room. 

And if you loose your dog, ask yourself why he always goes in that room to sleep. 

Ahhhh, the room.  The room is always the 3rd enclosure or something like that.  If you have a small room, you need bookshelf speakers.  Big honkin speakers in a small space isn't gonna work.  To put it another way, years ago, I had a buddy with an air cooled VW bug.  We were all into car stereos back then and he found this monstrous 30" woofer and he crammed that thing in the back seat with a massive Hifonics amp.  It sounded like crap in the car, but when we pulled inside the car stereo shop work-space bay, that thing absolutely rattled the door frames.  This reminds me of another story/example.  Back when Sound Stream was big, they introduced a massive 18" woofer in a cast frame and massive magnet; the shop owner built a special ported enclosure.  Inside the showroom, it was loud, but when we walked out of the room into the shop, that's when you really felt that thing hit.  Okay, enough rambling, if you got a crappy room, then nearfield listening is your only hope.  In nearfield listening, this is done with bookshelf speakers and you're say anywhere from 4-ish or so feet away.  A front ported speaker, is the trick.  If you can find one that is a dipole with an ambience driver (tweeter) in the rear firing position like many Von Schweikert speakers do, this help with the airy and ambiant presentation, which I enjoy a lot.  Good luck in your quest.