Not sure if I would qualify as 'low income' or not, but this thread inspired me to delurk, so ...
I'm an artist with a day job (and have been for quite some time.) Currently only make anywhere from $3-5K a year from art (which is the best I've ever done), so majority of my income is from the day job. I've spent most of my life hovering around the $30-40K mark in a very HCOL area (greater Seattle area), but always managed to make it work. I've always been conservative with money--never took out big loans, always saved up for things. But I didn't understand investing or anything other than having a few hundred saved for a rainy day, for the most part. My mindset from my 20's to mid-thirties was that if you weren't saving up FOR something (a move, Christmas presents, a car, whatever), or spending it, then what was money for anyway?
Then in 2006, with the urging of the parental units, I bought a condo. This turned out to be the worst possible time to buy--at the height of the market, right before the crash. If I'd only waited two more years--but, as other posters have said, hindsight is 20/20. I also lost my job two months after buying, which turned out to be a bit of a blessing in disguise. I lined up a new job quickly, but being jobless with two mortgages for even that brief period of time 'scared me straight', as it were. I started researching how to live on a budget, went from The Simple Dollar to Get Rich Slowly to MMM, which many side stops along the way at Bogleheads, Vanguard, etc. Started realizing that I could save 'for' something after all--the chance to be a full-time artist, rather than trying to squeeze it around a 40 hr a week job.
So I started cutting the fat, and putting whatever I had left over in an IRA/401K/emergency fund. MMM forums also started me aggressively pursuing salary bumps and better jobs, to the point that as of this year I'm making closer to 60K a year than 40 (which still doesn't go as far as I'd like as far as savings, but I love my HCOL area, so ....) Approx. 10 years later, am now very grateful for my condo because rents are skyrocketing around here, and thanks to some additional cashflow from an inheritance, may actually have it paid off in a few more years, at which point I could afford to go part-time on the day job.
I'm currently sitting at about a 30% savings rate (give or take--I'm HORRIBLE with numbers, even when the computer's doing all the work). I'm not a monk--I take at least one low-cost vacation a year, and buy the occasional techie toy or other indulgence (mostly off of Craigslist or Amazon). Occasionally I think of all the other fun toys/trips I could be buying with that 30% rather than socking it away where I can't touch it--but honestly, I'm very comfortable where I'm at, and I'm hoping my plan will pay off in the long run. *crosses fingers and hopes the ACA sticks around*